Computer Networks Questions & Answers – Congestion Control MCQ أسئله شبكات بالأجابات الجزء السادس والثلاثون

Computer Networks Questions & Answers – Congestion Control

1. Two broad categories of congestion control are
a) Open-loop and Closed-loop
b) Open-control and Closed-control
c) Active control and Passive control
d) None of the mentioned

Answer: a
Explanation: These are two types of congestion control.

2. In open-loop control, policies are applied to __________
a) Remove after congestion occurs
b) Remove after sometime
c) Prevent before congestion occurs
d) Prevent before sending packets

Answer: c
Explanation: Policies are applied to prevent congestion before it occurs.

3. Retransmission of packets must be done when
a) Packet is lost
b) Packet is corrupted
c) Packet is needed
d) All of the mentioned

Answer: d
Explanation: Retransmission should be done on account of any of the above cases.

4. In Go-Back-N window, when the timer of the packet times out, several packets have to be resent even some may have arrived safe. whereas in Selective Repeat window, tries to send ___________
a) Packet that have not lost
b) Packet that have lost or corrupted
c) Packet from starting
d) All the packets

Answer: b
Explanation: In selective repeat window, packet that have lost or corrupted must be sent.

5. Discarding policy is mainly done by
a) Sender
b) Receiver
c) Router
d) Switch

Answer: c
Explanation: This is done by the routers to prevent congestion.

6. Closed-Loop control mechanism try to
a) Remove after congestion occurs
b) Remove after sometime
c) Prevent before congestion occurs
d) Prevent before sending packets

Answer: a
Explanation: Policies are applied to remove congestion after it occurs.

7. The technique in which a congested node stops receiving data from the immediate upstream node or nodes is called as
a) Admission policy
b) Backpressure
c) Forward signalling
d) Backward signalling

Answer: b
Explanation: This is a node-to-node congestion control that starts with a node and propagates in opposite direction of data flow to the source.

8. Backpressure technique can be applied only to
a) Congestion networks
b) Closed circuit networks
c) Open circuit networks
d) Virtual circuit networks

Answer: d
Explanation: In Virtual circuit networks, each node knows the upstream node from which a flow data is coming.

9. The packet sent by a node to the source to inform it of congestion is called
a) Explicit
b) Discard
c) Choke
d) Backpressure

Answer: c
Explanation: Choke packet is sent by a node to the source to inform it of congestion.

10. In the slow-start algorithm, the size of the congestion window increases __________ until it reaches a threshold.
a) Exponentially
b) Additively
c) Multiplicatively
d) None of the mentioned

Answer: a
Explanation: In the slow-start algorithm, the size of the congestion window increases exponentially until it reaches a threshold.

11. In the congestion avoidance algorithm, the size of the congestion window increases ____________ until congestion is detected.
a) Exponentially
b) Additively
c) Multiplicatively
d) None of the mentioned

Answer: b
Explanation: In the congestion avoidance algorithm, the size of the congestion window increases additively until congestion is detected.

 

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