Comptia Network+ N10-009 Exam Cram (2024)
Comptia Network+ N10-009 Exam Cram (2024) simplifies exam prep with well-structured content and practice questions.
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CompTIA Network+ N10-009 Exam Cram
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both the online and desktop versions can be found on the companion website.
If you have any issues accessing the companion website or obtaining your Pearson
Test Prep practice test access code, you can contact our support team by going to
pearsonitp.echelp.org.
Companion Website and Pearson Test Prep Access Code
Access interactive study tools on this book’s companion website, including practice
test software, review exercises, Key Term flash card application, a study planner,
and more!
To access the companion website, simply follow these steps:
1. Go to www.pearsonITcertification.com/register.
2. Enter the print book ISBN: 9780135340837.
3. Answer the security question to validate your purchase.
4. Go to your account page.
5. Click on the Registered Products tab.
6. Under the book listing, click on the Access Bonus Content link.
When you register your book, your Pearson Test Prep practice test access code will
automatically be populated with the book listing under the Registered Products tab.
You will need this code to access the practice test that comes with this book. You
can redeem the code at PearsonTestPrep.com. Simply choose Pearson IT
Certification as your product group and log into the site with the same credentials
you used to register your book. Click the Activate New Product button and enter
the access code. More detailed instructions on how to redeem your access code for
both the online and desktop versions can be found on the companion website.
If you have any issues accessing the companion website or obtaining your Pearson
Test Prep practice test access code, you can contact our support team by going to
pearsonitp.echelp.org.
Loading page 4...
CompTIA® Network+ N10-009 Exam
Cram
Emmett Dulaney
Cram
Emmett Dulaney
Loading page 5...
CompTIA Network+ N10-009 Exam Cram
Copyright © 2025 by Pearson Education, Inc.
All rights reserved. No part of this book shall be reproduced, stored in a retrieval
system, or transmitted by any means, electronic, mechanical, photocopying,
recording, or otherwise, without written permission from the publisher. No patent
liability is assumed with respect to the use of the information contained herein.
Although every precaution has been taken in the preparation of this book, the
publisher and author assume no responsibility for errors or omissions. Nor is any
liability assumed for damages resulting from the use of the information contained
herein.
Please contact us with concerns about any potential bias at
https://www.pearson.com/report-bias.xhtml.
ISBN-13: 978-0-13-534083-7
ISBN-10: 0-13-534083-7
Library of Congress Control Number: 2024939808
ScoutAutomatedPrintCode
Trademarks
All terms mentioned in this book that are known to be trademarks or service marks
have been appropriately capitalized. Pearson IT Certification cannot attest to the
accuracy of this information. Use of a term in this book should not be regarded as
affecting the validity of any trademark or service mark.
Warning and Disclaimer
Every effort has been made to make this book as complete and as accurate as
possible, but no warranty or fitness is implied. The information provided is on an
"as is" basis. The author and the publisher shall have neither liability nor
responsibility to any person or entity with respect to any loss or damages arising
from the information contained in this book.
Special Sales
For information about buying this title in bulk quantities, or for special sales
opportunities (which may include electronic versions; custom cover designs; and
content particular to your business, training goals, marketing focus, or branding
interests), please contact our corporate sales department at
corpsales@pearsoned.com or (800) 382-3419.
For government sales inquiries, please contact governmentsales@pearsoned.com.
For questions about sales outside the U.S., please contact intlcs@pearson.com.
GM K12, Early Career and Professional Learning
Soo Kang
Copyright © 2025 by Pearson Education, Inc.
All rights reserved. No part of this book shall be reproduced, stored in a retrieval
system, or transmitted by any means, electronic, mechanical, photocopying,
recording, or otherwise, without written permission from the publisher. No patent
liability is assumed with respect to the use of the information contained herein.
Although every precaution has been taken in the preparation of this book, the
publisher and author assume no responsibility for errors or omissions. Nor is any
liability assumed for damages resulting from the use of the information contained
herein.
Please contact us with concerns about any potential bias at
https://www.pearson.com/report-bias.xhtml.
ISBN-13: 978-0-13-534083-7
ISBN-10: 0-13-534083-7
Library of Congress Control Number: 2024939808
ScoutAutomatedPrintCode
Trademarks
All terms mentioned in this book that are known to be trademarks or service marks
have been appropriately capitalized. Pearson IT Certification cannot attest to the
accuracy of this information. Use of a term in this book should not be regarded as
affecting the validity of any trademark or service mark.
Warning and Disclaimer
Every effort has been made to make this book as complete and as accurate as
possible, but no warranty or fitness is implied. The information provided is on an
"as is" basis. The author and the publisher shall have neither liability nor
responsibility to any person or entity with respect to any loss or damages arising
from the information contained in this book.
Special Sales
For information about buying this title in bulk quantities, or for special sales
opportunities (which may include electronic versions; custom cover designs; and
content particular to your business, training goals, marketing focus, or branding
interests), please contact our corporate sales department at
corpsales@pearsoned.com or (800) 382-3419.
For government sales inquiries, please contact governmentsales@pearsoned.com.
For questions about sales outside the U.S., please contact intlcs@pearson.com.
GM K12, Early Career and Professional Learning
Soo Kang
Loading page 6...
Executive Editor
Nancy Davis
Development Editor
Ellie Bru
Managing Editor
Sandra Schroeder
Senior Project Editor
Tonya Simpson
Copy Editor
Chuck Hutchinson
Indexer
Proofreader
Technical Editor
Chris Crayton
Publishing Coordinator
Cindy Teeters
Cover Designer
Chuti Prasertsith
Compositor
Nancy Davis
Development Editor
Ellie Bru
Managing Editor
Sandra Schroeder
Senior Project Editor
Tonya Simpson
Copy Editor
Chuck Hutchinson
Indexer
Proofreader
Technical Editor
Chris Crayton
Publishing Coordinator
Cindy Teeters
Cover Designer
Chuti Prasertsith
Compositor
Loading page 7...
Contents at a Glance
Introduction
1 Networking Models, Ports, Protocols, and Services
2 Network Topologies, Architectures, and Types
3 Network Addressing, Routing, and Switching
4 Network Implementations
5 Cabling Solutions and Issues
6 Wireless Solutions
7 Cloud Computing Concepts and Options
8 Network Operations
9 Network Security
10 Network Troubleshooting
Cram Sheet
Glossary
Introduction
1 Networking Models, Ports, Protocols, and Services
2 Network Topologies, Architectures, and Types
3 Network Addressing, Routing, and Switching
4 Network Implementations
5 Cabling Solutions and Issues
6 Wireless Solutions
7 Cloud Computing Concepts and Options
8 Network Operations
9 Network Security
10 Network Troubleshooting
Cram Sheet
Glossary
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Table of Contents
Introduction
About Network+ Exam Cram
About the Network+ Exam
Companion Website
How to Access the Pearson Test Prep (PTP) App
Assessing Exam Readiness
Chapter 1. Networking Models, Ports, Protocols, and Services
The OSI Networking Model
Ports, Protocols, Services, and Traffic Types
What’s Next?
Chapter 2. Network Topologies, Architectures, and Types
Network Topologies
What’s Next?
Chapter 3. Network Addressing, Routing, and Switching
IPv4 Network Addressing
Routing and Switching Technologies
Network Services
What’s Next?
Chapter 4. Network Implementations
Common Networking Devices
Networking Use Cases
What’s Next?
Chapter 5. Cabling Solutions and Issues
General Media Considerations
Troubleshooting Common Cable Connectivity Issues
Limitations, Considerations, and Issues
Hardware Issues
Common Tools
What’s Next?
Chapter 6. Wireless Solutions
Understanding Wireless Basics
What’s Next?
Chapter 7. Cloud Computing Concepts and Options
Cloud Concepts
What’s Next?
Chapter 8. Network Operations
Introduction
About Network+ Exam Cram
About the Network+ Exam
Companion Website
How to Access the Pearson Test Prep (PTP) App
Assessing Exam Readiness
Chapter 1. Networking Models, Ports, Protocols, and Services
The OSI Networking Model
Ports, Protocols, Services, and Traffic Types
What’s Next?
Chapter 2. Network Topologies, Architectures, and Types
Network Topologies
What’s Next?
Chapter 3. Network Addressing, Routing, and Switching
IPv4 Network Addressing
Routing and Switching Technologies
Network Services
What’s Next?
Chapter 4. Network Implementations
Common Networking Devices
Networking Use Cases
What’s Next?
Chapter 5. Cabling Solutions and Issues
General Media Considerations
Troubleshooting Common Cable Connectivity Issues
Limitations, Considerations, and Issues
Hardware Issues
Common Tools
What’s Next?
Chapter 6. Wireless Solutions
Understanding Wireless Basics
What’s Next?
Chapter 7. Cloud Computing Concepts and Options
Cloud Concepts
What’s Next?
Chapter 8. Network Operations
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Physical Installation Factors
Organizational Processes and Procedures
Monitoring Network Performance
Disaster Recovery and High Availability
Network Access and Management Methods
What’s Next?
Chapter 9. Network Security
Common Security Concepts
Common Networking Attacks
Applying Network Security
What’s Next?
Chapter 10. Network Troubleshooting
Troubleshooting Steps and Procedures
Troubleshooting Common Networking Issues
Troubleshooting Tools
What’s Next?
The Network+ Cram Sheet
Networking Concepts
Network Implementation
Network Operations
Network Security
Network Troubleshooting
Glossary
Organizational Processes and Procedures
Monitoring Network Performance
Disaster Recovery and High Availability
Network Access and Management Methods
What’s Next?
Chapter 9. Network Security
Common Security Concepts
Common Networking Attacks
Applying Network Security
What’s Next?
Chapter 10. Network Troubleshooting
Troubleshooting Steps and Procedures
Troubleshooting Common Networking Issues
Troubleshooting Tools
What’s Next?
The Network+ Cram Sheet
Networking Concepts
Network Implementation
Network Operations
Network Security
Network Troubleshooting
Glossary
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About the Author
Emmett Dulaney (CompTIA Network+, Cloud+, Security+, A+, and others) has
been the author of several books on certifications and operating systems over the
past 25 years. He is a columnist for Certification Magazine and a professor at a
small university in Indiana. He is currently the editor of a journal devoted to
business education (and the business of education).
Emmett Dulaney (CompTIA Network+, Cloud+, Security+, A+, and others) has
been the author of several books on certifications and operating systems over the
past 25 years. He is a columnist for Certification Magazine and a professor at a
small university in Indiana. He is currently the editor of a journal devoted to
business education (and the business of education).
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Dedication
For Harrison, Teresea, Wolfgang, and Elijah: never stop networking
—Emmett Dulaney
For Harrison, Teresea, Wolfgang, and Elijah: never stop networking
—Emmett Dulaney
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Acknowledgments
Thanks are due to Eleanor (Ellie) Bru for working on this title once more and
making it as strong as it can be. An enormous amount of credit for this book always
goes to Chris Crayton, who goes above and beyond what is expected and without
whom the resulting text would only be a shadow of what it is. It is an honor to work
with him. Thanks continue to be due to Mike Harwood, who wrote the first few
editions, and to the team of talented individuals at Pearson who work behind the
scenes and make each title the best it can be.
Thanks are due to Eleanor (Ellie) Bru for working on this title once more and
making it as strong as it can be. An enormous amount of credit for this book always
goes to Chris Crayton, who goes above and beyond what is expected and without
whom the resulting text would only be a shadow of what it is. It is an honor to work
with him. Thanks continue to be due to Mike Harwood, who wrote the first few
editions, and to the team of talented individuals at Pearson who work behind the
scenes and make each title the best it can be.
Loading page 13...
About the Technical Reviewer
Chris Crayton, MCSE, CISSP, CASP+, PenTest+, Project+, CySA+, Cloud+, S+,
N+, A+, ITF+ is a technical consultant, trainer, author, and industry-leading
technical editor. He has worked as a computer technology and networking
instructor, information security director, network administrator, network engineer,
and PC specialist. Chris has served as technical editor and content contributor on
numerous technical titles for several of the leading publishing companies. He has
also been recognized with many professional and teaching awards, and has served
as a state-level SkillsUSA final competition judge.
Chris Crayton, MCSE, CISSP, CASP+, PenTest+, Project+, CySA+, Cloud+, S+,
N+, A+, ITF+ is a technical consultant, trainer, author, and industry-leading
technical editor. He has worked as a computer technology and networking
instructor, information security director, network administrator, network engineer,
and PC specialist. Chris has served as technical editor and content contributor on
numerous technical titles for several of the leading publishing companies. He has
also been recognized with many professional and teaching awards, and has served
as a state-level SkillsUSA final competition judge.
Loading page 14...
We Want to Hear from You!
As the reader of this book, you are our most important critic and commentator. We
value your opinion and want to know what we're doing right, what we could do
better, what areas you'd like to see us publish in, and any other words of wisdom
you're willing to pass our way.
We welcome your comments. You can email or write to let us know what you did
or didn't like about this book—as well as what we can do to make our books better.
Please note that we cannot help you with technical problems related to the topic of
this book.
When you write, please be sure to include this book’s title and author as well as
your name and email address. We will carefully review your comments and share
them with the author and editors who worked on the book.
Email: community@informit.com
As the reader of this book, you are our most important critic and commentator. We
value your opinion and want to know what we're doing right, what we could do
better, what areas you'd like to see us publish in, and any other words of wisdom
you're willing to pass our way.
We welcome your comments. You can email or write to let us know what you did
or didn't like about this book—as well as what we can do to make our books better.
Please note that we cannot help you with technical problems related to the topic of
this book.
When you write, please be sure to include this book’s title and author as well as
your name and email address. We will carefully review your comments and share
them with the author and editors who worked on the book.
Email: community@informit.com
Loading page 15...
Reader Services
Register your copy of CompTIA Network+ N10-009 Exam Cram for convenient
access to downloads, updates, and corrections as they become available. To start
the registration process, go to www.pearsonitcertification.com/register and log in or
create an account*. Enter the product ISBN 9780135340837 and click Submit.
When the process is complete, you will find any available bonus content under
Registered Products.
*Be sure to check the box that you would like to hear from us to receive exclusive
discounts on future editions of this product.
Register your copy of CompTIA Network+ N10-009 Exam Cram for convenient
access to downloads, updates, and corrections as they become available. To start
the registration process, go to www.pearsonitcertification.com/register and log in or
create an account*. Enter the product ISBN 9780135340837 and click Submit.
When the process is complete, you will find any available bonus content under
Registered Products.
*Be sure to check the box that you would like to hear from us to receive exclusive
discounts on future editions of this product.
Loading page 16...
Introduction
Welcome to CompTIA Network+ N10-009 Exam Cram. This book is designed to
prepare you to take—and pass—the CompTIA Network+ exam. The Network+
exam has become the leading introductory-level network certification available
today. It is recognized by both employers and industry giants as providing
candidates with a solid foundation of networking concepts, terminology, and skills.
The Network+ exam covers a broad range of networking concepts to prepare
candidates for the technologies they are likely to work with in today’s network
environments.
About Network+ Exam Cram
Exam Crams are designed to give you the information you need to know to prepare
for a certification exam. They cut through the extra information, focusing on the
areas you need to get through the exam. With this in mind, the elements within the
Exam Cram titles are aimed at providing the exam information you need in the
most succinct and accessible manner.
In this light, this book is organized to closely follow the actual CompTIA
objectives for exam N10-009. As such, it is easy to find the information required
for each of the specified CompTIA Network+ objectives. The objective focus
design used by this Exam Cram is an important feature because the information you
need to know is easily identifiable and accessible. To see what we mean, compare
the CompTIA objectives to the book’s layout, and you can see that the facts are
right where you would expect them to be.
Within the chapters, potential exam hotspots are clearly highlighted with Exam
Alerts. They have been carefully placed to let you know that the surrounding
discussion is an important area for the exam. To further help you prepare for the
exam, a Cram Sheet is included that you can use in the final stages of test
preparation. Be sure to pay close attention to the bulleted points on the Cram Sheet
because they pinpoint the technologies and facts you probably will encounter on
the test.
Finally, great effort has gone into the questions that appear throughout the chapter
and the practice tests to ensure that they accurately represent the look and feel of
the ones you will see on the real Network+ exam. Be sure, before taking the exam,
that you are comfortable with both the format and content of the questions provided
in this book.
About the Network+ Exam
The Network+ (N10-009 Edition) exam is the newest iteration of several versions
of the exam. The new Network+ objectives are aimed toward those who have at
least nine to twelve months of experience in the IT networking field. While it is
Welcome to CompTIA Network+ N10-009 Exam Cram. This book is designed to
prepare you to take—and pass—the CompTIA Network+ exam. The Network+
exam has become the leading introductory-level network certification available
today. It is recognized by both employers and industry giants as providing
candidates with a solid foundation of networking concepts, terminology, and skills.
The Network+ exam covers a broad range of networking concepts to prepare
candidates for the technologies they are likely to work with in today’s network
environments.
About Network+ Exam Cram
Exam Crams are designed to give you the information you need to know to prepare
for a certification exam. They cut through the extra information, focusing on the
areas you need to get through the exam. With this in mind, the elements within the
Exam Cram titles are aimed at providing the exam information you need in the
most succinct and accessible manner.
In this light, this book is organized to closely follow the actual CompTIA
objectives for exam N10-009. As such, it is easy to find the information required
for each of the specified CompTIA Network+ objectives. The objective focus
design used by this Exam Cram is an important feature because the information you
need to know is easily identifiable and accessible. To see what we mean, compare
the CompTIA objectives to the book’s layout, and you can see that the facts are
right where you would expect them to be.
Within the chapters, potential exam hotspots are clearly highlighted with Exam
Alerts. They have been carefully placed to let you know that the surrounding
discussion is an important area for the exam. To further help you prepare for the
exam, a Cram Sheet is included that you can use in the final stages of test
preparation. Be sure to pay close attention to the bulleted points on the Cram Sheet
because they pinpoint the technologies and facts you probably will encounter on
the test.
Finally, great effort has gone into the questions that appear throughout the chapter
and the practice tests to ensure that they accurately represent the look and feel of
the ones you will see on the real Network+ exam. Be sure, before taking the exam,
that you are comfortable with both the format and content of the questions provided
in this book.
About the Network+ Exam
The Network+ (N10-009 Edition) exam is the newest iteration of several versions
of the exam. The new Network+ objectives are aimed toward those who have at
least nine to twelve months of experience in the IT networking field. While it is
Loading page 17...
helpful if Network+ candidates should have A+ certification (or its equivalent), it is
not required, and this should not discourage those who do not.
You will have a maximum of 90 minutes to answer the 90 questions on the exam.
The allotted time is quite generous, so when you finish, you probably will have
time to double-check a few of the answers you were unsure of.
By the time the dust settles, you need a minimum score of 720 to pass the Network
+ exam. This is on a scale of 100 to 900. For more information on the specifics of
the Network+ exam, refer to CompTIA’s main website at
http://certification.comptia.org/.
CompTIA Network+ Exam Topics
Table I-1 lists general exam topics (that is, objectives) and specific topics under
each general topic (that is, subobjectives) for the CompTIA Network+ N10-009
exam. This table also lists the chapter in which each exam topic is covered.
Table I.1 CompTIA Network+ Exam Topics
Booking and Taking the Network+ Certification Exam
Unfortunately, testing is not free. You’re charged for each test you take, whether
you pass or fail. In the United States and Canada, tests are administered by Pearson
VUE testing services. To access the VUE contact information and book an exam,
refer to the website at http://www.pearsonvue.com or call 1-877-551-7587. When
booking an exam, you need to provide the following information:
• Your name as you would like it to appear on your certificate.
• Your Social Security or Social Insurance number.
• Contact phone numbers (to be called in case of a problem).
• Mailing address, which identifies the address to which you want your
certificate mailed.
• Exam number and title.
• Email address for contact purposes. This often is the fastest and most effective
means to contact you. Test vendors require it for registration.
• Credit card information so that you can pay online. You can redeem vouchers
by calling the respective testing center.
What to Expect from the Exam
If you haven’t taken a certification test, the process can be a little unnerving. Even
if you’ve taken numerous tests, it is not much better. Mastering the inner mental
game often can be as much of a battle as knowing the material. Knowing what to
expect before heading in can make the process a little more comfortable.
not required, and this should not discourage those who do not.
You will have a maximum of 90 minutes to answer the 90 questions on the exam.
The allotted time is quite generous, so when you finish, you probably will have
time to double-check a few of the answers you were unsure of.
By the time the dust settles, you need a minimum score of 720 to pass the Network
+ exam. This is on a scale of 100 to 900. For more information on the specifics of
the Network+ exam, refer to CompTIA’s main website at
http://certification.comptia.org/.
CompTIA Network+ Exam Topics
Table I-1 lists general exam topics (that is, objectives) and specific topics under
each general topic (that is, subobjectives) for the CompTIA Network+ N10-009
exam. This table also lists the chapter in which each exam topic is covered.
Table I.1 CompTIA Network+ Exam Topics
Booking and Taking the Network+ Certification Exam
Unfortunately, testing is not free. You’re charged for each test you take, whether
you pass or fail. In the United States and Canada, tests are administered by Pearson
VUE testing services. To access the VUE contact information and book an exam,
refer to the website at http://www.pearsonvue.com or call 1-877-551-7587. When
booking an exam, you need to provide the following information:
• Your name as you would like it to appear on your certificate.
• Your Social Security or Social Insurance number.
• Contact phone numbers (to be called in case of a problem).
• Mailing address, which identifies the address to which you want your
certificate mailed.
• Exam number and title.
• Email address for contact purposes. This often is the fastest and most effective
means to contact you. Test vendors require it for registration.
• Credit card information so that you can pay online. You can redeem vouchers
by calling the respective testing center.
What to Expect from the Exam
If you haven’t taken a certification test, the process can be a little unnerving. Even
if you’ve taken numerous tests, it is not much better. Mastering the inner mental
game often can be as much of a battle as knowing the material. Knowing what to
expect before heading in can make the process a little more comfortable.
Loading page 18...
Certification tests are administered on a computer system at a VUE authorized
testing center. The format of the exams is straightforward: each question has
several possible answers to choose from. The questions in this book provide a good
example of the types of questions you can expect on the exam. If you are
comfortable with them, the test should hold few surprises. Many of the questions
vary in length. Some of them are longer scenario questions, whereas others are
short and to the point. Carefully read the questions; the longer questions often have
a key point that will lead you to the correct answer.
Most of the questions on the Network+ exam require you to choose a single correct
answer, but a few require multiple answers. When there are multiple correct
answers, a message at the bottom of the screen prompts you to “Choose all that
apply.” Be sure to read these messages.
A Few Exam-Day Details
It is recommended that you arrive at the examination room at least 15 minutes
early, although a few minutes earlier certainly would not hurt. This will give you
time to prepare and will give the test administrator time to answer any questions
you might have before the test begins. Many people suggest that you review the
most critical information about the test you’re taking just before the test. (Exam
Cram books provide a reference—the Cram Sheet, located inside the front of this
book—that lists the essential information from the book in distilled form.) Arriving
a few minutes early will give you some time to compose yourself and mentally
review this critical information.
You will be asked to provide two forms of ID, one of which must be a photo ID.
Both of the identifications you choose should have a signature. You also might
need to sign in when you arrive and sign out when you leave.
Be warned: The rules are clear about what you can and cannot take into the
examination room. Books, laptops, note sheets, and so on are not allowed in the
examination room. The test administrator will hold these items, to be returned after
you complete the exam. You might receive either a wipe board or a pen and a
single piece of paper for making notes during the exam. The test administrator will
ensure that no paper is removed from the examination room.
After the Test
Whether you want it or not, as soon as you finish your test, your score displays on
the computer screen. In addition to the results appearing on the computer screen, a
hard copy of the report prints for you. Like the onscreen report, the hard copy
displays the results of your exam and provides a summary of how you did on each
section and on each technology. If you were unsuccessful, this summary can help
you determine the areas you need to brush up on.
When you pass the Network+ exam, you will have earned the Network+
certification, and your certificate will be mailed to you within a few weeks. Should
you not receive your certificate and information packet within five weeks of
testing center. The format of the exams is straightforward: each question has
several possible answers to choose from. The questions in this book provide a good
example of the types of questions you can expect on the exam. If you are
comfortable with them, the test should hold few surprises. Many of the questions
vary in length. Some of them are longer scenario questions, whereas others are
short and to the point. Carefully read the questions; the longer questions often have
a key point that will lead you to the correct answer.
Most of the questions on the Network+ exam require you to choose a single correct
answer, but a few require multiple answers. When there are multiple correct
answers, a message at the bottom of the screen prompts you to “Choose all that
apply.” Be sure to read these messages.
A Few Exam-Day Details
It is recommended that you arrive at the examination room at least 15 minutes
early, although a few minutes earlier certainly would not hurt. This will give you
time to prepare and will give the test administrator time to answer any questions
you might have before the test begins. Many people suggest that you review the
most critical information about the test you’re taking just before the test. (Exam
Cram books provide a reference—the Cram Sheet, located inside the front of this
book—that lists the essential information from the book in distilled form.) Arriving
a few minutes early will give you some time to compose yourself and mentally
review this critical information.
You will be asked to provide two forms of ID, one of which must be a photo ID.
Both of the identifications you choose should have a signature. You also might
need to sign in when you arrive and sign out when you leave.
Be warned: The rules are clear about what you can and cannot take into the
examination room. Books, laptops, note sheets, and so on are not allowed in the
examination room. The test administrator will hold these items, to be returned after
you complete the exam. You might receive either a wipe board or a pen and a
single piece of paper for making notes during the exam. The test administrator will
ensure that no paper is removed from the examination room.
After the Test
Whether you want it or not, as soon as you finish your test, your score displays on
the computer screen. In addition to the results appearing on the computer screen, a
hard copy of the report prints for you. Like the onscreen report, the hard copy
displays the results of your exam and provides a summary of how you did on each
section and on each technology. If you were unsuccessful, this summary can help
you determine the areas you need to brush up on.
When you pass the Network+ exam, you will have earned the Network+
certification, and your certificate will be mailed to you within a few weeks. Should
you not receive your certificate and information packet within five weeks of
Loading page 19...
passing your exam, contact CompTIA at fulfillment@comptia.org, or call 1-630-
678-8300 and ask for the fulfillment department.
Last-Minute Exam Tips
Studying for a certification exam is no different than studying for any other exam,
but a few hints and tips can give you the edge on exam day:
• Read all the material: CompTIA has been known to include material not
expressly specified in the objectives. This book has included additional
information not reflected in the objectives to give you the best possible
preparation for the examination.
• Watch for the Exam Tips and Notes: The Network+ objectives include a
wide range of technologies. ExamAlerts, Tips, and Notes found throughout
each chapter are designed to pull out exam-related hotspots. These can be your
best friends when preparing for the exam.
• Use the questions to assess your knowledge: Don’t just read the chapter
content; use the exam questions to find out what you know and what you
don’t. If you struggle, study some more, review, and then assess your
knowledge again.
• Review the exam objectives: Develop your own questions and examples for
each topic listed. If you can develop and answer several questions for each
topic, you should not find it difficult to pass the exam.
Good luck!
Companion Website
Register this book to get access to the Pearson Test Prep practice test software and
other study materials plus additional bonus content. Check this site regularly for
new and updated postings written by the author that provide further insight into the
more troublesome topics on the exams. Be sure to check the box that you would
like to hear from us to receive updates and exclusive discounts on future editions of
this product or related products.
To access this companion website, follow these steps:
1. Go to www.pearsonITcertification.com/register and log in or create a new
account.
2. Enter the ISBN: 9780135340837.
3. Answer the challenge question as proof of purchase.
4. Click the Access Bonus Content link in the Registered Products section of
your account page, to be taken to the page where your downloadable content
is available.
Please note that many of our companion content files can be very large, especially
image and video files.
678-8300 and ask for the fulfillment department.
Last-Minute Exam Tips
Studying for a certification exam is no different than studying for any other exam,
but a few hints and tips can give you the edge on exam day:
• Read all the material: CompTIA has been known to include material not
expressly specified in the objectives. This book has included additional
information not reflected in the objectives to give you the best possible
preparation for the examination.
• Watch for the Exam Tips and Notes: The Network+ objectives include a
wide range of technologies. ExamAlerts, Tips, and Notes found throughout
each chapter are designed to pull out exam-related hotspots. These can be your
best friends when preparing for the exam.
• Use the questions to assess your knowledge: Don’t just read the chapter
content; use the exam questions to find out what you know and what you
don’t. If you struggle, study some more, review, and then assess your
knowledge again.
• Review the exam objectives: Develop your own questions and examples for
each topic listed. If you can develop and answer several questions for each
topic, you should not find it difficult to pass the exam.
Good luck!
Companion Website
Register this book to get access to the Pearson Test Prep practice test software and
other study materials plus additional bonus content. Check this site regularly for
new and updated postings written by the author that provide further insight into the
more troublesome topics on the exams. Be sure to check the box that you would
like to hear from us to receive updates and exclusive discounts on future editions of
this product or related products.
To access this companion website, follow these steps:
1. Go to www.pearsonITcertification.com/register and log in or create a new
account.
2. Enter the ISBN: 9780135340837.
3. Answer the challenge question as proof of purchase.
4. Click the Access Bonus Content link in the Registered Products section of
your account page, to be taken to the page where your downloadable content
is available.
Please note that many of our companion content files can be very large, especially
image and video files.
Loading page 20...
Step 1.
Step 2.
Step 3.
If you are unable to locate the files for this title by following these steps, please
visit www.pearsonITcertification.com/contact and select the Site
Problems/Comments option. Our customer service representatives will assist you.
How to Access the Pearson Test Prep (PTP) App
You have two options for installing and using the Pearson Test Prep application: a
web app and a desktop app. To use the Pearson Test Prep application, start by
accessing the registration code that comes with the book. You can access the code
in these ways:
• You can get your access code by registering the print ISBN 9780135340837 on
https://www.pearsonitcertification.com/register. Make sure to use the print
book ISBN, regardless of whether you purchased an eBook or the print book.
After you register the book, your access code will be populated on your
account page under the Registered Products tab. Instructions for how to
redeem the code are available on the book’s companion website by clicking
the Access Bonus Content link.
• If you purchase the Premium Edition eBook and Practice Test directly from the
Pearson IT Certification website, the code will be populated on your account
page after purchase. Just log in at https://www.pearsonitcertification.com,
click Account to see details of your account, and click the Digital Purchases
tab.
Note
After you register your book, your code can always be found in your
account under the Registered Products tab.
Once you have the access code, to find instructions about both the PTP web app
and the desktop app, follow these steps:
Open this book’s companion website as shown on the first page of the
book.
Click the Practice Exams button.
Follow the instructions listed there for both installing the desktop app and
using the web app.
Note that if you want to use the web app only at this point, just navigate to
https://www.pearsontestprep.com, log in using the same credentials used to register
your book or purchase the Premium Edition, and register for this book’s practice
tests using the registration code you just found. The process should take only a
couple of minutes.
Customizing Your Exams
After you are in the exam settings screen, you can choose to take exams in one of
three modes:
Step 2.
Step 3.
If you are unable to locate the files for this title by following these steps, please
visit www.pearsonITcertification.com/contact and select the Site
Problems/Comments option. Our customer service representatives will assist you.
How to Access the Pearson Test Prep (PTP) App
You have two options for installing and using the Pearson Test Prep application: a
web app and a desktop app. To use the Pearson Test Prep application, start by
accessing the registration code that comes with the book. You can access the code
in these ways:
• You can get your access code by registering the print ISBN 9780135340837 on
https://www.pearsonitcertification.com/register. Make sure to use the print
book ISBN, regardless of whether you purchased an eBook or the print book.
After you register the book, your access code will be populated on your
account page under the Registered Products tab. Instructions for how to
redeem the code are available on the book’s companion website by clicking
the Access Bonus Content link.
• If you purchase the Premium Edition eBook and Practice Test directly from the
Pearson IT Certification website, the code will be populated on your account
page after purchase. Just log in at https://www.pearsonitcertification.com,
click Account to see details of your account, and click the Digital Purchases
tab.
Note
After you register your book, your code can always be found in your
account under the Registered Products tab.
Once you have the access code, to find instructions about both the PTP web app
and the desktop app, follow these steps:
Open this book’s companion website as shown on the first page of the
book.
Click the Practice Exams button.
Follow the instructions listed there for both installing the desktop app and
using the web app.
Note that if you want to use the web app only at this point, just navigate to
https://www.pearsontestprep.com, log in using the same credentials used to register
your book or purchase the Premium Edition, and register for this book’s practice
tests using the registration code you just found. The process should take only a
couple of minutes.
Customizing Your Exams
After you are in the exam settings screen, you can choose to take exams in one of
three modes:
Loading page 21...
• Study Mode: Enables you to fully customize your exams and review answers
as you are taking the exam. This is typically the mode you would use first to
assess your knowledge and identify information gaps.
• Practice Exam Mode: Locks certain customization options because it is
presenting a realistic exam experience. Use this mode when you are preparing
to test your exam readiness.
• Flash Card Mode: Strips out the answers and presents you with only the
question stem. This mode is great for late-stage preparation when you really
want to challenge yourself to provide answers without the benefit of seeing
multiple-choice options. This mode will not provide the detailed score reports
that the other two modes will, so it should not be used if you are trying to
identify knowledge gaps.
In addition to these three modes, you will be able to select the source of your
questions. You can choose to take exams that cover all the chapters, or you can
narrow your selection to a single chapter or the chapters that make up specific parts
in the book. All chapters are selected by default. If you want to narrow your focus
to individual chapters, first deselect all the chapters; then select only those on
which you want to focus in the Objectives area.
You can also select the exam banks on which to focus. Each exam bank comes
complete with a full exam of questions that cover topics in every chapter. The two
exams printed in the book are available to you as well as two additional exams of
unique questions. You can have the test engine serve up exams from all four banks
or just from one individual bank by selecting the desired banks in the exam bank
area.
You can make several other customizations to your exam from the exam settings
screen, such as the time of the exam, the number of questions, whether to
randomize questions and answers, whether to show the number of correct answers
for multiple answer questions, or whether to serve up only specific types of
questions. You can also create custom test banks by selecting only questions that
you have marked or questions on which you have added notes.
Updating Your Exams
If you are using the online version of the Pearson Test Prep software, you should
always have access to the latest version of the software as well as the exam data. If
you are using the Windows desktop version, every time you launch the software, it
will check to see if there are any updates to your exam data and automatically
download any changes that were made since the last time you used the software.
This requires that you are connected to the Internet at the time you launch the
software.
Sometimes, due to many factors, the exam data may not fully download when you
activate your exam. If you find that figures or exhibits are missing, you may need
to manually update your exams.
as you are taking the exam. This is typically the mode you would use first to
assess your knowledge and identify information gaps.
• Practice Exam Mode: Locks certain customization options because it is
presenting a realistic exam experience. Use this mode when you are preparing
to test your exam readiness.
• Flash Card Mode: Strips out the answers and presents you with only the
question stem. This mode is great for late-stage preparation when you really
want to challenge yourself to provide answers without the benefit of seeing
multiple-choice options. This mode will not provide the detailed score reports
that the other two modes will, so it should not be used if you are trying to
identify knowledge gaps.
In addition to these three modes, you will be able to select the source of your
questions. You can choose to take exams that cover all the chapters, or you can
narrow your selection to a single chapter or the chapters that make up specific parts
in the book. All chapters are selected by default. If you want to narrow your focus
to individual chapters, first deselect all the chapters; then select only those on
which you want to focus in the Objectives area.
You can also select the exam banks on which to focus. Each exam bank comes
complete with a full exam of questions that cover topics in every chapter. The two
exams printed in the book are available to you as well as two additional exams of
unique questions. You can have the test engine serve up exams from all four banks
or just from one individual bank by selecting the desired banks in the exam bank
area.
You can make several other customizations to your exam from the exam settings
screen, such as the time of the exam, the number of questions, whether to
randomize questions and answers, whether to show the number of correct answers
for multiple answer questions, or whether to serve up only specific types of
questions. You can also create custom test banks by selecting only questions that
you have marked or questions on which you have added notes.
Updating Your Exams
If you are using the online version of the Pearson Test Prep software, you should
always have access to the latest version of the software as well as the exam data. If
you are using the Windows desktop version, every time you launch the software, it
will check to see if there are any updates to your exam data and automatically
download any changes that were made since the last time you used the software.
This requires that you are connected to the Internet at the time you launch the
software.
Sometimes, due to many factors, the exam data may not fully download when you
activate your exam. If you find that figures or exhibits are missing, you may need
to manually update your exams.
Loading page 22...
To update a particular exam you have already activated and downloaded, select the
Tools tab and then click the Update Products button. Again, this is an issue only
with the desktop Windows application.
If you want to check for updates to the Pearson Test Prep exam engine software,
Windows desktop version, select the Tools tab and click the Update Application
button. This will ensure that you are running the latest version of the software
engine.
Assessing Exam Readiness
Exam candidates never really know whether they are adequately prepared for the
exam until they have completed about 30 percent of the questions. At that point, if
you are not prepared, it is too late. The best way to determine your readiness is to
work through the CramSaver quizzes at the beginning of each chapter and review
the exam objectives and ExamAlerts presented in each chapter. It is best to work
your way through the entire book unless you can complete each subject without
having to do any research or look up any answers.
Tools tab and then click the Update Products button. Again, this is an issue only
with the desktop Windows application.
If you want to check for updates to the Pearson Test Prep exam engine software,
Windows desktop version, select the Tools tab and click the Update Application
button. This will ensure that you are running the latest version of the software
engine.
Assessing Exam Readiness
Exam candidates never really know whether they are adequately prepared for the
exam until they have completed about 30 percent of the questions. At that point, if
you are not prepared, it is too late. The best way to determine your readiness is to
work through the CramSaver quizzes at the beginning of each chapter and review
the exam objectives and ExamAlerts presented in each chapter. It is best to work
your way through the entire book unless you can complete each subject without
having to do any research or look up any answers.
Loading page 23...
Figure Credits
This content is currently in development.
This content is currently in development.
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Chapter 1. Networking Models, Ports,
Protocols, and Services
This chapter covers the following official Network+ objectives:
• 1.1 Explain concepts related to the Open Systems Interconnection (OSI)
reference model.
• 1.4 Explain common networking ports, protocols, services, and traffic
types.
This chapter covers CompTIA Network+ objectives 1.1, and 1.4. For more
information on the official Network+ exam topics, see the “About the Network
+ Exam” section in the Introduction.
One of the most important networking concepts to understand is the Open Systems
Interconnection (OSI) reference model. This conceptual model, created by the
International Organization for Standardization (ISO) in 1978 and revised in 1984,
describes a network architecture that enables data to be passed between computer
systems.
This chapter looks at the OSI model and describes how it relates to real-world
networking. It also examines how common network devices relate to the OSI
model. Even though the OSI model is conceptual, an appreciation of its purpose
and function can help you better understand how protocol suites and network
architectures work in practical applications.
Note
The TCP/IP model, which performs the same functions as the OSI model,
except in four layers instead of seven, is not a standalone Network+
objective, but this is the protocol suite predominantly in use today, and
you should have a solid understanding of it since so many other
objectives are based on it. Since it is still important to know it to
understand the underlying principles of networking, we refer to it where
it is appropriate to do so.
The OSI Networking Model
• 1.1 Explain concepts related to the Open Systems Interconnection (OSI)
reference model.
Protocols, and Services
This chapter covers the following official Network+ objectives:
• 1.1 Explain concepts related to the Open Systems Interconnection (OSI)
reference model.
• 1.4 Explain common networking ports, protocols, services, and traffic
types.
This chapter covers CompTIA Network+ objectives 1.1, and 1.4. For more
information on the official Network+ exam topics, see the “About the Network
+ Exam” section in the Introduction.
One of the most important networking concepts to understand is the Open Systems
Interconnection (OSI) reference model. This conceptual model, created by the
International Organization for Standardization (ISO) in 1978 and revised in 1984,
describes a network architecture that enables data to be passed between computer
systems.
This chapter looks at the OSI model and describes how it relates to real-world
networking. It also examines how common network devices relate to the OSI
model. Even though the OSI model is conceptual, an appreciation of its purpose
and function can help you better understand how protocol suites and network
architectures work in practical applications.
Note
The TCP/IP model, which performs the same functions as the OSI model,
except in four layers instead of seven, is not a standalone Network+
objective, but this is the protocol suite predominantly in use today, and
you should have a solid understanding of it since so many other
objectives are based on it. Since it is still important to know it to
understand the underlying principles of networking, we refer to it where
it is appropriate to do so.
The OSI Networking Model
• 1.1 Explain concepts related to the Open Systems Interconnection (OSI)
reference model.
Loading page 25...
CramSaver
If you can correctly answer these questions before going through this
section, save time by skimming the ExamAlerts in this section and then
completing the Cram Quiz at the end of the section.
1. Which layer of the OSI model converts data from the application layer
into a format that can be sent over the network?
2. True or false: Transport protocols, such as UDP, map to the transport
layer of the OSI model and are responsible for transporting data across
the network.
3. At what layer of the OSI model do HTTP and SSH map?
Answers
1. The presentation layer converts data from the application layer into a
format that can be sent over the network. It also converts data from the
session layer into a format the application layer can understand.
2. True. Transport protocols map to the transport layer of the OSI model
and are responsible for transporting data across the network. UDP is a
transport protocol.
3. HTTP and SSH (along with many other protocols) map to the
application layer of the OSI model.
For networking, two models commonly are referenced: the OSI model and the
TCP/IP model. Both offer a framework, theoretical and actual, for how networking
is implemented. Objective 1.1 of the Network+ exam focuses only on the OSI
model. A thorough discussion of it follows with a brief discussion of the TCP/IP
model tossed in for further understanding.
The OSI Seven-Layer Model
As shown in Figure 1.1, the OSI reference model is built, bottom to top, in the
following order: physical, data link, network, transport, session, presentation, and
application. The physical layer is classified as Layer 1, and the top layer of the
model, the application layer, is Layer 7.
ExamAlert
The OSI model can be used as a bottom-to-top troubleshooting tool. For
example, troubleshooting a network interface card (NIC) or network
wiring would begin at Layer 1, the physical layer where electrical
functions support physical connections. If the problem is not found there,
If you can correctly answer these questions before going through this
section, save time by skimming the ExamAlerts in this section and then
completing the Cram Quiz at the end of the section.
1. Which layer of the OSI model converts data from the application layer
into a format that can be sent over the network?
2. True or false: Transport protocols, such as UDP, map to the transport
layer of the OSI model and are responsible for transporting data across
the network.
3. At what layer of the OSI model do HTTP and SSH map?
Answers
1. The presentation layer converts data from the application layer into a
format that can be sent over the network. It also converts data from the
session layer into a format the application layer can understand.
2. True. Transport protocols map to the transport layer of the OSI model
and are responsible for transporting data across the network. UDP is a
transport protocol.
3. HTTP and SSH (along with many other protocols) map to the
application layer of the OSI model.
For networking, two models commonly are referenced: the OSI model and the
TCP/IP model. Both offer a framework, theoretical and actual, for how networking
is implemented. Objective 1.1 of the Network+ exam focuses only on the OSI
model. A thorough discussion of it follows with a brief discussion of the TCP/IP
model tossed in for further understanding.
The OSI Seven-Layer Model
As shown in Figure 1.1, the OSI reference model is built, bottom to top, in the
following order: physical, data link, network, transport, session, presentation, and
application. The physical layer is classified as Layer 1, and the top layer of the
model, the application layer, is Layer 7.
ExamAlert
The OSI model can be used as a bottom-to-top troubleshooting tool. For
example, troubleshooting a network interface card (NIC) or network
wiring would begin at Layer 1, the physical layer where electrical
functions support physical connections. If the problem is not found there,
Loading page 26...
then the next step would be to run a loopback test on the NIC (moving up
to Layer 2), and so on.
Figure 1.1 The OSI Seven-Layer Model
ExamAlert
On the Network+ exam, you might see an OSI layer referenced either by
its name, such as network layer, or by its layer number. For instance, you
might find that a router is referred to as a Layer 3 device. An easy
mnemonic that you can use to remember the layers from top to bottom is:
All People Seem To Need Data Processing.
Each layer of the OSI model has a specific function. The following sections
describe the function of each layer, starting with the physical layer and working up
the model.
Physical Layer (Layer 1)
The physical layer of the OSI model identifies the network’s physical
characteristics, including the following specifications:
• Hardware: The type of media used on the network, such as type of cable, type
of connector, and pinout format for cables.
• Topology: The physical layer identifies the topology to be used in the network.
Common topologies today include mesh, star/hub and spoke, spine and leaf,
point-to-point and hybrid, and these are discussed in Chapter 2.
Protocols and technologies such as USB, Ethernet, Bluetooth, DSL, ISDN, T-
carrier links (T1 and T3), GSM, and Integrated Services Digital Networks (ISDN)
operate at the physical layer.
In addition to these characteristics, the physical layer defines the voltage used on a
given medium and the frequency at which the signals that carry the data operate.
These characteristics dictate the speed and bandwidth of a given medium, as well
as the maximum distance over which a certain media type can be used.
Data Link Layer (Layer 2)
The data link layer is responsible for getting data to the physical layer so that it can
transmit over the network. The data link layer is also responsible for error
detection, error correction, and hardware addressing. The term frame describes the
logical grouping of data at the data link layer.
The data link layer has two distinct sublayers:
• Media Access Control (MAC) layer: The MAC address is defined at this
layer. The MAC address is the physical or hardware address burned into each
to Layer 2), and so on.
Figure 1.1 The OSI Seven-Layer Model
ExamAlert
On the Network+ exam, you might see an OSI layer referenced either by
its name, such as network layer, or by its layer number. For instance, you
might find that a router is referred to as a Layer 3 device. An easy
mnemonic that you can use to remember the layers from top to bottom is:
All People Seem To Need Data Processing.
Each layer of the OSI model has a specific function. The following sections
describe the function of each layer, starting with the physical layer and working up
the model.
Physical Layer (Layer 1)
The physical layer of the OSI model identifies the network’s physical
characteristics, including the following specifications:
• Hardware: The type of media used on the network, such as type of cable, type
of connector, and pinout format for cables.
• Topology: The physical layer identifies the topology to be used in the network.
Common topologies today include mesh, star/hub and spoke, spine and leaf,
point-to-point and hybrid, and these are discussed in Chapter 2.
Protocols and technologies such as USB, Ethernet, Bluetooth, DSL, ISDN, T-
carrier links (T1 and T3), GSM, and Integrated Services Digital Networks (ISDN)
operate at the physical layer.
In addition to these characteristics, the physical layer defines the voltage used on a
given medium and the frequency at which the signals that carry the data operate.
These characteristics dictate the speed and bandwidth of a given medium, as well
as the maximum distance over which a certain media type can be used.
Data Link Layer (Layer 2)
The data link layer is responsible for getting data to the physical layer so that it can
transmit over the network. The data link layer is also responsible for error
detection, error correction, and hardware addressing. The term frame describes the
logical grouping of data at the data link layer.
The data link layer has two distinct sublayers:
• Media Access Control (MAC) layer: The MAC address is defined at this
layer. The MAC address is the physical or hardware address burned into each
Loading page 27...
NIC. The MAC sublayer also controls access to network media. The MAC
layer specification is included in the IEEE 802.1 standard.
• Logical Link Control (LLC) layer: The LLC layer is responsible for the error
and flow-control mechanisms of the data link layer. The LLC layer is
specified in the IEEE 802.2 standard.
Protocols and technologies such as High-Level Data Link Control (HDLC), Layer 2
Tunneling Protocol (L2TP), Point-to-Point Protocol (PPP), Point-to-Point
Tunneling Protocol (PPTP), Spanning Tree Protocol (STP), and virtual LANs
(VLANs) operate at the data link layer.
Network Layer (Layer 3)
The primary responsibility of the network layer is routing—providing mechanisms
by which data can be passed from one network system to another. The network
layer does not specify how the data is passed but rather provides the mechanisms to
do so. Functionality at the network layer is provided through routing protocols,
which are software components.
Protocols at the network layer are also responsible for route selection, which refers
to determining the best path for the data to take throughout the network. The
network layer contains Internet Protocol (IP) headers. In contrast to the data link
layer, which uses MAC addresses to communicate on the LAN, network layer
protocols use software-configured addresses and special routing protocols to
communicate on the network. The term packet describes the logical grouping of
data at the network layer.
When you’re working with networks, routes can be configured in two ways:
statically or dynamically. In a static routing environment, routes are manually
added to the routing tables. In a dynamic routing environment, routing protocols
such as Routing Information Protocol (RIP) and Open Shortest Path First (OSPF)
are used. These protocols communicate routing information between networked
devices on the network. Other important network layer protocols include Internet
Protocol (IP), Address Resolution Protocol (ARP), Reverse Address Resolution
Protocol (RARP), Asynchronous Transfer Mode (ATM), Intermediate System-to-
Intermediate System (IS-IS), IP Security (IPsec), Internet Control Message
Protocol (ICMP), and Multiprotocol Label Switching (MPLS).
Transport Layer (Layer 4)
The basic function of the transport layer is to provide mechanisms to transport data
between network devices. Primarily, it does this in three ways:
• Error checking: Protocols at the transport layer ensure that data is correctly
sent or received.
• Service addressing: A number of protocols support many network services.
The transport layer ensures that data is passed to the right service at the upper
layers of the OSI model.
layer specification is included in the IEEE 802.1 standard.
• Logical Link Control (LLC) layer: The LLC layer is responsible for the error
and flow-control mechanisms of the data link layer. The LLC layer is
specified in the IEEE 802.2 standard.
Protocols and technologies such as High-Level Data Link Control (HDLC), Layer 2
Tunneling Protocol (L2TP), Point-to-Point Protocol (PPP), Point-to-Point
Tunneling Protocol (PPTP), Spanning Tree Protocol (STP), and virtual LANs
(VLANs) operate at the data link layer.
Network Layer (Layer 3)
The primary responsibility of the network layer is routing—providing mechanisms
by which data can be passed from one network system to another. The network
layer does not specify how the data is passed but rather provides the mechanisms to
do so. Functionality at the network layer is provided through routing protocols,
which are software components.
Protocols at the network layer are also responsible for route selection, which refers
to determining the best path for the data to take throughout the network. The
network layer contains Internet Protocol (IP) headers. In contrast to the data link
layer, which uses MAC addresses to communicate on the LAN, network layer
protocols use software-configured addresses and special routing protocols to
communicate on the network. The term packet describes the logical grouping of
data at the network layer.
When you’re working with networks, routes can be configured in two ways:
statically or dynamically. In a static routing environment, routes are manually
added to the routing tables. In a dynamic routing environment, routing protocols
such as Routing Information Protocol (RIP) and Open Shortest Path First (OSPF)
are used. These protocols communicate routing information between networked
devices on the network. Other important network layer protocols include Internet
Protocol (IP), Address Resolution Protocol (ARP), Reverse Address Resolution
Protocol (RARP), Asynchronous Transfer Mode (ATM), Intermediate System-to-
Intermediate System (IS-IS), IP Security (IPsec), Internet Control Message
Protocol (ICMP), and Multiprotocol Label Switching (MPLS).
Transport Layer (Layer 4)
The basic function of the transport layer is to provide mechanisms to transport data
between network devices. Primarily, it does this in three ways:
• Error checking: Protocols at the transport layer ensure that data is correctly
sent or received.
• Service addressing: A number of protocols support many network services.
The transport layer ensures that data is passed to the right service at the upper
layers of the OSI model.
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• Segmentation: To traverse the network, blocks of data need to be broken into
packets of a manageable size for the lower layers to handle. This process,
called segmentation, is the responsibility of the transport layer.
Protocols that operate at the transport layer can either be connectionless, such as
User Datagram Protocol (UDP), or connection oriented, such as Transmission
Control Protocol (TCP).
The transport layer is also responsible for data flow control, which refers to how
the receiving device can accept data transmissions. Two common methods of flow
control are used:
• Buffering: When buffering flow control is used, data is temporarily stored and
waits for the destination device to become available. Buffering can cause a
problem if the sending device transmits data much faster than the receiving
device can manage.
• Windowing: In a windowing environment, data is sent in groups of segments
that require only one acknowledgment. The size of the window (that is, how
many segments fit into one acknowledgment) is defined when the session
between the two devices is established. As you can imagine, the need to have
only one acknowledgment for every five segments, for instance, can greatly
reduce overhead.
Session Layer (Layer 5)
The session layer is responsible for managing and controlling the synchronization
of data between applications on two devices. It does this by establishing,
maintaining, and breaking sessions. Whereas the transport layer is responsible for
setting up and maintaining the connection between the two nodes (devices), the
session layer performs the same function on behalf of the application. In other
words, conversations between applications are established, coordinated, and
terminated at the session layer.
Protocols that operate at the session layer include NetBIOS, Network File System
(NFS), and Server Message Block (SMB).
Presentation Layer (Layer 6)
The presentation layer’s basic function is to convert the data intended for or
received from the application layer into another format. Such conversion is
necessary because of how data is formatted so that it can be transported across the
network. Applications cannot necessarily read this conversion. Some common data
formats handled by the presentation layer include the following:
• Graphics files: JPEG, TIFF, GIF, and so on are graphics file formats that
require the data to be formatted in a certain way.
• Text and data: The presentation layer can translate data into different formats,
such as American Standard Code for Information Interchange (ASCII) and
Extended Binary Coded Decimal Interchange Code (EBCDIC).
packets of a manageable size for the lower layers to handle. This process,
called segmentation, is the responsibility of the transport layer.
Protocols that operate at the transport layer can either be connectionless, such as
User Datagram Protocol (UDP), or connection oriented, such as Transmission
Control Protocol (TCP).
The transport layer is also responsible for data flow control, which refers to how
the receiving device can accept data transmissions. Two common methods of flow
control are used:
• Buffering: When buffering flow control is used, data is temporarily stored and
waits for the destination device to become available. Buffering can cause a
problem if the sending device transmits data much faster than the receiving
device can manage.
• Windowing: In a windowing environment, data is sent in groups of segments
that require only one acknowledgment. The size of the window (that is, how
many segments fit into one acknowledgment) is defined when the session
between the two devices is established. As you can imagine, the need to have
only one acknowledgment for every five segments, for instance, can greatly
reduce overhead.
Session Layer (Layer 5)
The session layer is responsible for managing and controlling the synchronization
of data between applications on two devices. It does this by establishing,
maintaining, and breaking sessions. Whereas the transport layer is responsible for
setting up and maintaining the connection between the two nodes (devices), the
session layer performs the same function on behalf of the application. In other
words, conversations between applications are established, coordinated, and
terminated at the session layer.
Protocols that operate at the session layer include NetBIOS, Network File System
(NFS), and Server Message Block (SMB).
Presentation Layer (Layer 6)
The presentation layer’s basic function is to convert the data intended for or
received from the application layer into another format. Such conversion is
necessary because of how data is formatted so that it can be transported across the
network. Applications cannot necessarily read this conversion. Some common data
formats handled by the presentation layer include the following:
• Graphics files: JPEG, TIFF, GIF, and so on are graphics file formats that
require the data to be formatted in a certain way.
• Text and data: The presentation layer can translate data into different formats,
such as American Standard Code for Information Interchange (ASCII) and
Extended Binary Coded Decimal Interchange Code (EBCDIC).
Loading page 29...
• Sound/video: MPEG, MP3, and MIDI files all have their own data formats to
and from which data must be converted.
Another important function of the presentation layer is encryption, which is the
scrambling of data so that it can’t be read by anyone other than the intended
recipient. Given the basic role of the presentation layer—that of data-format
translator—it is the obvious place for encryption and decryption to take place. For
example, the cryptographic protocol Transport Layer Security (TLS) operates at the
presentation layer.
Application Layer (Layer 7)
In simple terms, the function of the application layer is to take requests and data
from the users and pass them to the lower layers of the OSI model. Incoming
information is passed to the application layer, which then displays the information
to the users. Some of the most basic application layer services include file and print
capabilities.
The most common misconception about the application layer is that it represents
applications used on a system, such as a web browser, word processor, or
spreadsheet. Instead, the application layer defines the processes that enable
applications to use network services. For example, if an application needs to open a
file from a network drive, the functionality is provided by components that reside at
the application layer. Protocols defined at the application layer include Secure Shell
(SSH), Border Gateway Protocol (BGP), Dynamic Host Configuration Protocol
(DHCP), Domain Name System (DNS), Network Time Protocol (NTP), Real-time
Transport Protocol (RTP), Session Initiation Protocol (SIP), Simple Mail Transfer
Protocol (SMTP), Server Message Block (SMB), File Transfer Protocol (FTP),
Hypertext Transfer Protocol (HTTP), Hypertext Transfer Protocol Secure
(HTTPS), Internet Message Access Protocol (IMAP), and Post Office Protocol
version 3 (POP3).
ExamAlert
Be sure you understand the OSI model and its purpose. You will almost
certainly be asked questions on it during the exam. Know Table 1.1 well!
OSI Model Summary
Table 1.1 summarizes the seven layers of the OSI model and describes some of the
most significant points of each layer.
Table 1.1 OSI Model Summary
Comparing OSI to the Four-Layer TCP/IP Model
The OSI model does a fantastic job outlining how networking should occur and the
responsibility of each layer. However, TCP/IP also has a reference model and has
and from which data must be converted.
Another important function of the presentation layer is encryption, which is the
scrambling of data so that it can’t be read by anyone other than the intended
recipient. Given the basic role of the presentation layer—that of data-format
translator—it is the obvious place for encryption and decryption to take place. For
example, the cryptographic protocol Transport Layer Security (TLS) operates at the
presentation layer.
Application Layer (Layer 7)
In simple terms, the function of the application layer is to take requests and data
from the users and pass them to the lower layers of the OSI model. Incoming
information is passed to the application layer, which then displays the information
to the users. Some of the most basic application layer services include file and print
capabilities.
The most common misconception about the application layer is that it represents
applications used on a system, such as a web browser, word processor, or
spreadsheet. Instead, the application layer defines the processes that enable
applications to use network services. For example, if an application needs to open a
file from a network drive, the functionality is provided by components that reside at
the application layer. Protocols defined at the application layer include Secure Shell
(SSH), Border Gateway Protocol (BGP), Dynamic Host Configuration Protocol
(DHCP), Domain Name System (DNS), Network Time Protocol (NTP), Real-time
Transport Protocol (RTP), Session Initiation Protocol (SIP), Simple Mail Transfer
Protocol (SMTP), Server Message Block (SMB), File Transfer Protocol (FTP),
Hypertext Transfer Protocol (HTTP), Hypertext Transfer Protocol Secure
(HTTPS), Internet Message Access Protocol (IMAP), and Post Office Protocol
version 3 (POP3).
ExamAlert
Be sure you understand the OSI model and its purpose. You will almost
certainly be asked questions on it during the exam. Know Table 1.1 well!
OSI Model Summary
Table 1.1 summarizes the seven layers of the OSI model and describes some of the
most significant points of each layer.
Table 1.1 OSI Model Summary
Comparing OSI to the Four-Layer TCP/IP Model
The OSI model does a fantastic job outlining how networking should occur and the
responsibility of each layer. However, TCP/IP also has a reference model and has
Loading page 30...
to perform the same functionality with only four layers. Figure 1.2 shows how
these four layers line up with the seven layers of the OSI model.
Figure 1.2 The TCP/IP Model Compared to the OSI Model
The network interface layer in the TCP/IP model is sometimes referred to as the
network access or link layer, and this is where Ethernet, wireless networks, network
interface cards (NICs), or any other physical technology can run. The Internet layer
is where IP runs (along with ICMP and others). The transport layer is where TCP
and its counterpart UDP operate. The application layer enables any number of
protocols to be plugged in, such as HTTP, SMTP, Simple Network Management
Protocol (SNMP), DNS, and many others.
Identifying the OSI Layers at Which Various Network
Components Operate
When you understand the OSI model, you can relate network connectivity devices
to the appropriate layer of the OSI model. Knowing at which OSI layer a device
operates enables you to better understand how it functions on the network. Table
1.2 identifies various network devices and maps them to the OSI model.
ExamAlert
For the Network+ exam, you are expected to identify at which layer of
the OSI model certain network devices operate.
Table 1.2 Mapping Network Devices to the OSI Model
Data Encapsulation/Decapsulation and OSI
As data moves down the model (and through the devices on that host), it is
encapsulated with a header added to the beginning and a trailer to the end. Once the
data arrives at the receiving host, it moves up the model (and through the devices)
and is decapsulated in that the header and trailer are stripped off as it moves up.
Note
There are a great many topics beneath exam objective 1.1. In the interest
of our discussion building in a logical way, the focus here is still on the
networking model in order to complete the discussion of it. Later in this
chapter, we visit headers again and some of the other topics the
objectives include but that do not fit well with the dialogue yet.
ExamAlert
these four layers line up with the seven layers of the OSI model.
Figure 1.2 The TCP/IP Model Compared to the OSI Model
The network interface layer in the TCP/IP model is sometimes referred to as the
network access or link layer, and this is where Ethernet, wireless networks, network
interface cards (NICs), or any other physical technology can run. The Internet layer
is where IP runs (along with ICMP and others). The transport layer is where TCP
and its counterpart UDP operate. The application layer enables any number of
protocols to be plugged in, such as HTTP, SMTP, Simple Network Management
Protocol (SNMP), DNS, and many others.
Identifying the OSI Layers at Which Various Network
Components Operate
When you understand the OSI model, you can relate network connectivity devices
to the appropriate layer of the OSI model. Knowing at which OSI layer a device
operates enables you to better understand how it functions on the network. Table
1.2 identifies various network devices and maps them to the OSI model.
ExamAlert
For the Network+ exam, you are expected to identify at which layer of
the OSI model certain network devices operate.
Table 1.2 Mapping Network Devices to the OSI Model
Data Encapsulation/Decapsulation and OSI
As data moves down the model (and through the devices on that host), it is
encapsulated with a header added to the beginning and a trailer to the end. Once the
data arrives at the receiving host, it moves up the model (and through the devices)
and is decapsulated in that the header and trailer are stripped off as it moves up.
Note
There are a great many topics beneath exam objective 1.1. In the interest
of our discussion building in a logical way, the focus here is still on the
networking model in order to complete the discussion of it. Later in this
chapter, we visit headers again and some of the other topics the
objectives include but that do not fit well with the dialogue yet.
ExamAlert
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CompTIA Certifications