Chapter 1. Introduction to TCP/IP Networking

Question 1

1. Which of the following protocols are examples of TCP/IP transport layer protocols? (Choose two answers.)
   a. Ethernet
   b. HTTP
   c. IP
   d. UDP
   e. SMTP
   f. TCP

Answer 1

D and F. Of the remaining answers, Ethernet defines both physical and data-link proto-cols, PPP is a data-link protocol, IP is a network layer protocol, and SMTP and HTTP are application layer protocols.

Question 2

2. Which of the following protocols are examples of TCP/IP data-link layer protocols? (Choose two answers.)
   a. Ethernet
   b. HTTP
   c. IP
   d. UDP
   e. SMTP
   f. TCP
   g. PPP

Answer 2

A and G. Of the remaining answers, IP is a network layer protocol, TCP and UDP are transport layer protocols, and SMTP and HTTP are application layer protocols.

Question 3

3. The process of HTTP asking TCP to send some data and making sure that it is received correctly is an example of what?
   a. Same-layer interaction
   b. Adjacent-layer interaction
   c. OSI model
   d. All of these answers are correct.

Answer 3

B. Adjacent-layer interaction occurs on one computer, with two adjacent layers in the model. The higher layer requests services from the next lower layer, and the lower layer provides the services to the next higher layer.

Question 4

4. The process of TCP on one computer marking a TCP segment as segment 1, and the receiving computer then acknowledging the receipt of TCP segment 1 is an example of what?
   a. Data encapsulation
   b. Same-layer interaction
   c. Adjacent-layer interaction
   d. OSI model
   e. All of these answers are correct.

Answer 4

B. Same-layer interaction occurs on multiple computers. The functions defined by that layer typically need to be accomplished by multiple computers—for example, the sender setting a sequence number for a segment and the receiver acknowledging receipt of that segment. A single layer defines that process, but the implementation of that layer on multiple devices is required to accomplish the function.

Question 5

5. The process of a web server adding a TCP header to the contents of a web page, fol-lowed by adding an IP header and then adding a data-link header and trailer, is an example of what?
   a. Data encapsulation
   b. Same-layer interaction
   c. OSI model
   d. All of these answers are correct.

Answer 5

A. Encapsulation is defined as the process of adding a header in front of data supplied by a higher layer (and possibly adding a trailer as well).

Question 6

6. Which of the following terms is used specifically to identify the entity created when encapsulating data inside data-link layer headers and trailers?
   a. Data
   b. Chunk
   c. Segment
   d. Frame
   e. Packet

Answer 6

D. By convention, the term frame refers to the part of a network message that includes the data-link header and trailer, with encapsulated data. The term packet omits the data-link header and trailer, leaving the network layer header with its encapsulated data. The term segment omits the network layer header, leaving the transport layer header and its encapsulated data.

Question 7

7. Which OSI encapsulation term can be used instead of the term frame?
   a. Layer 1 PDU
   b. Layer 2 PDU
   c. Layer 3 PDU
   d. Layer 5 PDU
   e. Layer 7 PDU

Answer 7

B. The term frame refers to the data-link (that is, Layer 2) data structure created by a Layer 2 protocol. As a result, the matching OSI term for protocol data units (PDUs) mentions that same layer, that is, Layer 2 PDU, or L2PDU.