Figure: Historical Progression: Proprietary Models to the Open TCP/IP Model
Q1. 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: D and F. Of the remaining answers, Ethernet defines both physical and data link protocols, PPP is a data link protocol, IP is a network layer protocol, and SMTP and HTTP are application layer protocols.
Q2. 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: 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.
Q3. 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: 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.
Q4. 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: 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.
Q5. The process of a web server adding a TCP header to the contents of a web page, followed 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: 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).
Q6. 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: 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.
Q7. Which OSI layer defines the functions of logical network-wide addressing and routing? a. Layer 1 b. Layer 2 c. Layer 3 d. Layer 4 e. Layer 5, 6, or 7
Answer: C. The network layer concerns itself with delivery of data over the complete endto-end path. That requires a way to identify each device, using addresses, and the addresses must be logical addresses that are therefore not tied to the physical details of the network.
Q8. Which OSI layer defines the standards for cabling and connectors? a. Layer 1 b. Layer 2 c. Layer 3 d. Layer 4 e. Layer 5, 6, or 7
Answer: A. The OSI physical layer includes all standards that specify the shape of connectors, wiring in cabling, electrical details, and encoding that the electrical signals use to encode bits over a cable.
Q9. Which of the following are not valid terms for the names of the seven OSI layers? (Choose two answers.) a. Application b. Data link c. Transmission d. Presentation e. Internet f. Session
Answer: C and E. The layer names, from top to bottom, are application, presentation, session, transport, network, data link, and physical.