ESAT Forouzan - Chapter 11: Data Link Control and Protocols

Question 1

In a Go-Back-N ARQ, 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

Answer 1

a. 0 to 63

Question 2

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

Answer 2

c. Overflow of the receiver buffer

Question 3

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. 6
c. 7
d. Any of the above

Answer 3

d. Any of the above

Question 4

For a sliding window of size n - 1 (n sequence numbers), there can be a maximum of _______ frames sent but unacknowledged.
a. 0
b. n – 1
c. n
d. n + 1

Answer 4

c. n

Question 5

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 Repeat
d. (a) and (b)

Answer 5

b. Go-Back-N

Question 6

ARQ stands for _______.
a. Automatic repeat quantization
b. Automatic repeat request
c. Automatic retransmission request
d. Acknowledge repeat request

Answer 6

b. Automatic repeat request

Question 7

A timer is set when _______ is (are) sent out.
a. A data frame
b. An ACK
c. A NAK
d. All the above

Answer 7

a. A data frame

Question 8

For Stop-and-Wait ARQ, for n data packets sent, _______ acknowledgments are needed.
a. n
b. 2n
c. n - 1
d. n + 1

Answer 8

a. n

Question 9

HDLC is an acronym for _______.
a. High-duplex line communication
b. High-level data link control
c. Half-duplex digital link combination
d. Host double-level circuit

Answer 9

b. High-level data link control

Question 10

The address field of a frame in HDLC protocol contains the address of the _______ station.
a. Primary
b. Secondary
c. Tertiary
d. (a) or (b)

Answer 10

b. Secondary

Question 11

The HDLC _______ field defines the beginning and end of a frame.
a. Flag
b. Address
c. Control
d. FCS

Answer 11

a. Flag

Question 12

What is present in all HDLC control fields?
a. P/F bit
b. N(R)
c. N(S)
d. Code bits

Answer 12

a. P/F bit

Question 13

The shortest frame in HDLC protocol is usually the _______ frame.
a. Information
b. Supervisory
c. Management
d. None of the above

Answer 13

b. Supervisory

Question 14

14. When data and acknowledgment are sent on the same frame, this is called _______.
    a. Piggybacking
    b. Backpacking
    c. Piggypacking
    d. A good idea

Answer 14

a. Piggybacking