1. Problem Session

2. Sniffer http://www.distinct.com

3. Problems
1) The ________ model shows how the network functions of a computer ought to be organized. A) ITU-T B) OSI C) ISO D) ANSI
2) The OSI model consists of ________ layers. A) three B) five C) seven D) eight
3) The ________ layer decides the location of synchronization points. A) network B) transport C) session D) presentation

4. 4) The ________ layer is the layer closest to the transmission medium
4) The ________ layer is the layer closest to the transmission medium. A) physical B) data link C) network D) transport
5) In the _________ layer, the data unit is called a frame. A) physical B) data link C) network D) transport
6) When different programs are running at the same time on a computer, they can be identified by their _________ addresses. A) node B) station C) service point (port) D) source

5. 7) Decryption and encryption of data are the responsibility of the _______ layer. A) physical B) data link C) presentation D) session
8) Node-to-node delivery of the data unit is the responsibility of the _______ layer. A) physical B) data link C) transport D) network
9) As the data packet moves from the lower to the upper layers, headers are ________. A) added B) subtracted C)rearranged D) modified

6. 10) As the data packet moves from the upper to the lower layers, headers are ________. A) added B) removed C) rearranged D) modified
11) The ________ layer lies between the network layer and the session layer. A) physical B) data link C) transport D) presentation
12) Layer 2 lies between the physical layer and the _______ layer. A) network B) data link C) transport D) presentation

7. 13) When data are transmitted from device A to device B, the header from A’s layer 5 is read by B’s ________ layer. A) physical B) transport C) session D) presentation
14) In the ________ layer, translations from one character code to another occur. A) transport B) session C) presentation D) application
15) The ________ layer changes bits into electromagnetic signals. A) physical B) data link C) transport D) presentation

8. 16) The ________ layer can use the trailer of the frame for error detection. A) physical B) data link C) transport D) presentation
17) How are OSI and ISO related to each other?
18) Match the following to one or more layers of the seven OSI layers: A) route determination B) flow control C) access to the network for the end user D) formatting data from one code to another E) switching

9. 19) Match the following to one or more of the seven OSI layers:
19) Match the following to one or more of the seven OSI layers: A) provides reliable end-to-end transmission of entire message B) defines frames C) provides user services such as electronic mail and file transfer D) transmits signals across physical medium
20) Match the following to one or more of the seven OSI layers: A) direct communication with user’s application program B) error correction and retransmission C) mechanical, electrical, and functional interface D) responsibility for node-to-node delivery of a frame E) reassembly of data packets into a message

10. 21) Match the following to one or more of the seven OSI layers:
21) Match the following to one or more of the seven OSI layers: A) provides format and code conversion services B) establishes, manages, and terminates sessions C) oversees end-to-end transmission of data packets D) provides verification of log-in and log-out E) provides independence from differences in data representation
22) Compare and contrast the delivery of data units in the data link layer, the network layer, and the transport layer.
23) The secondary device in a multipoint configuration sends data in response to ___________. A) an ACK B) an ENQ C) a poll D) a SEL

11. 24) In sliding window flow control, if the window size is 63, what is the range of sequence numbers? A) 0 to 63 B) 0 to 64 C) 1 to 63 D) 1 to 64
25) In sliding window flow control, the frames to the left of the receiver window are frames __________. A) received but not acknowledged B) received and acknowledged C) not received D) not sent
26) Regulation of the rate of transmission of data frames is known as _________. A) line discipline B) flow discipline C) data rate control D) switch control

12. 27) The retransmission of damaged or lost frames in the data link layer is known as _________. A) error control B) error conditioning C) line discipline D) flow control
28) Flow control is needed to prevent ___________. A) bit errors B) overflow of the sender buffer C) overflow of the receiver buffer D) collision between sender and receiver
29) In go-back-n ARQ, if frames 4, 5, and 6 are received successfully, the receiver may send an ACK ________ to the sender. A) 5 B) C) 7 D) any of the above

13. 30) For a sliding window of buffer size n, there can be a maximum of _________ frames sent but unacknowledged. A) 0 B) n-1 C) n D) n+1
31) An ACK 3 is sliding window flow control (window size of 8) means that frame _________ is next expected by the receiver. A) 2 B) 3 C) 4 D) 8
32) In stop-and-wait ARQ, if data 1 has an error, the receiver sends a _________ frame. A) NAK 0 B) NAK 1 C) NAK 2 D) NAK

14. 33) In ________ ARQ, when a NAK is received, all frames sent since the last frame acknowledged are retransmitted. A) stop-and-wait B) go-back-n C) selective-reject D) a and b
34) In _______ ARQ, if a NAK is received, only the specific damaged or lost frame is retransmitted. A) stop-and-wait B) go-back-n C) selective-reject D) a and b
35) ARQ stands for ________. A) automatic repeat quantization B) automatic repeat request C) automatic retransmission request D) acknowledge repeat request

15. 36) Draw the sender and receiver windows for a system using go-back-n ARQ given the following: A) frame 0 is sent; frame 0 is acknowledged B) frames 1 and 2 are sent; frames 1 and 2 are acknowledged C) frames 3, 4, and 5 are sent; NAK 4 is received D) frames 4, 5, and 6 are sent; frames 4 through 7 are acknowledged.
37) Repeat problem 48 using selective-reject ARQ.

16. 38) What does the number on a NAK frame mean for: A) stop-and-wait ARQ? B) go-back-n ARQ? C) selective-reject ARQ?
39) What does the number on an ACK frame mean for: A) stop-and-wait ARQ? B) go-back-n ARQ? C) selective-reject ARQ?
40) ACK 7 has been received by the sender in a sliding window system. Now frames 7, 0, 1, 2, and 3 are sent. For each of the following separate scenarios, discuss the significance of the receiving of: A) an ACK 1 B) an ACK 4 C) an ACK 3 D) a NAK 1 E) a NAK 3 E) a NAK 7

17. 41) End-to-end delivery is the movement of a message from _______
41) End-to-end delivery is the movement of a message from _______. A) one station to the next station B) one network to the next network C) source to destination D) non of the above
42) What type of addressing is specifically used by the transport layer? A) station addresses B) network addresses C) application program port addresses D) dialog addresses

18. 43) In ________ services, connections must be established and terminated. A) connectionless B) connection-oriented C) segmentation D) none of the above
44) In ________ services, no connection establishment is needed. A) connectionless B) connection-oriented C) segmentation D) none of the above
45) A virtual circuit is associated with a _________ service. A) connectionless B) connection-oriented C) segmentation D) none of the above

19. 46) In _________ services, packets of a single transmission travel from source to destination via different paths. A) connectionless B) connection-oriented C) segmentation D) none of the above
47) Show by calculation how many networks (not hosts) each IP address class (A, B, and C only) can have.
48) Show by calculation how many hosts per network each IP address class (A, B, and C only) can have.
49) Write the binary form of the following internet addresses: A) B) C) D)

20. 50) Find the class of the following host addresses: A) 121. 56. 3. 67
50) Find the class of the following host addresses: A) B) C) D)
51) Find the network address of each host address in the preceding problem.
52) Draw an internet with the following specifications. Show all of the hosts, their addresses, and connections. The address selection is up to you. A) one token ring network with four hosts (Class A) B) one Ethernet with four hosts (Class C) C) the token ring is connected to the Ethernet by a gateway