CIS3360: Security in Computing Homework 4 1. (32 points) Knowledge - based Question: a. How many layers are used in defining the Internet protocol stack? Please give their names from the top layer to the bottom layer. There are 4 layers in the Internet protocol stack which is mentioned below from the top layer to the bottom layer : - 1. Application layer (process - to - process) 2. Transport layer (host - to - host) 3. Internet layer (internetworking) 4. Link layer b. What is the size of TCP packet header? Size of UDP packet header? What layer do they belong to? In the TCP header, the Data Offset field specifies the size of the TCP header in 32 - bit words . The size of a UDP header is 8 bytes. Both TCP and UDP are transport protocols, belonging to the Transport Layer of the OSI model. Both TCP and UDP run on top of IP that operates at the Network layer. c. Each TCP connection is uniquely identified by what four terms? What is the smallest and largest value for each of the term? Class A Network - binary address start with 0, therefore the decimal number can be anywhere from 1 to 126. The first 8 bits (the first octet) identify the network and the remaining 24 bits indicate the host within the network. An example of a Class A IP address is 102.168.212.226, where "102" identifies the network and "168.212.226" identifies the host on that network. Class B Network - binary addresses start with 10, therefore the decimal number can be anywhere from 128 to 191. (The number 127 is reserved for loopback and is used for internal testing on the local machine.) The first 16 bits (the first two octets) identify the network and the remaining 16 bits indicate the host within the network. An example of a Class B IP address is 168.212.226.204 where "168.212" identifies the network and "226.204" identifies the host on that network. Class C Network - binary addresses start with 110, therefore the decimal number can be anywhere from 192 to 223. The first 24 bits (the first three octets) identify the network and the remaining 8 bits indicate the host within the network. An example of a Class C IP address is 200.168.212.226 where "200.168.212" identifies the network and "226" identifies the host on that network. Class D Network - binary addresses start with 1110, therefore the decimal number can be anywhere from 224 to 239. Class D networks are used to support multicasting.