Classical

Computer Networks - Data Communication & Network Security

86:  

The number of cross-points needed for 10 lines in a cross-point switch which is full duplex in nature and there are no self connection, is

A.

100

B.

45

C.

50

D.

90

 
 

Option: B

Explanation :

The number of cross points required for n lines in cross point switch which is full duplex in nature is n*(n-1) / 2 for 10 lines it is (10 * 9)/2 = 45 cross points. 


87:  

A group of 2m - 1 routers are interconnected in a centralized binary tree. With router at each tree node. Router I communicates with router J by sending a message to the root of the tree. If root then sends the message back down J, the mean path length will be

A.

2 (m - 2)

B.

2 (2m - 1)

C.

m - 1

D.

(2m - 1)/mJ

 
 

Option: A

Explanation :


88:  

 A circuit switching network has the following characteristics :

Set up time = 5 sec
Propagation = 5 sec
Message size = 1 M bits
Data transmission rate = 1 M bits
Data transmission rate = 1
Kbps Number of hops = 10

When will the last bit of the message reach the receiver ?

A.

t = 520 sec

B.

t = 1000 ms

C.

t = 250 sec

D.

t = 1025 sec

 
 

Option: D

Explanation :


89:  

Two networks each provide reliable connection-oriented service. One of them offers a reliable byte stream and the other offers a reliable message stream. A process writes 1024 bytes, then

A.

both networks will receive 2048 bytes as a single unit

B.

message stream network will receive 1024 bytes only at one time. But byte stream network will receive 2048 bytes as a single unit.

C.

message stream network receives 2048 bytes as a whole. But bytes stream 1024 bytes only at a time.

D.

both will receive 1024 bytes at one time since there is a gap between writes

 
 

Option: B

Explanation :


90:  

A packet switching network (highly loaded) has  the following characteristics:

Propagation delay = 2 sec/hp.
Data transmission rate = 1.
Packet size = r bit = 512 bits.
Number of of hops = 10.

At what time the last bit of the last packet will reach the receiver ?

A.

1024.5 sec

B.

1038 sec

C.

2048 sec

D.

512 sec

 
 

Option: A

Explanation :




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