Question from computer network
1)
Which layer converts bit into electromagnetic signals?
A)
Physical
B)
Network
C)
Transport
D)
Session
2)
Which of the following transmission media is not readily suitable to CSMA operation?
A)
Radio
B)
Twisted pair
C)
Fibre optic
D)
Coaxial
উত্তর:-
Radio
বিবরণ:-Wireless medium can’t be used for CSMA operations as they are not suitable for collision detection methods. As radio already have a large number of users, it can’t detect the collisions between the senders and the receivers. it is used in lan technologies where there is a physical wire.
3)
Phase transition for each bit is used is
A)
NRZ encoding
B)
Manchester encoding
C)
Carrier modulation
D)
Amplitude modulation
উত্তর:-
Manchester encoding
বিবরণ:-In the Manchester encoding, a logic 0 is indicated by a 0 to 1 transition at the centre of the bit and a logic 1 is indicated by a 1 to 0 transition at the centre of the bit.
Original Data Value Sent
Logic 0 0 to 1 (upward transition at bit centre)
Logic 1 1 to 0 (downward transition at bit centre)
For example, The pattern of bits " 0 1 1 1 1 0 0 1 ", the Manchester code will be 01 10 10 10 10 01 01 10
4)
Router solicitation and advertisement message is used by
A)
IP
B)
ARP
C)
ICMP
D)
DHCP
5)
Exponential increase is used in
A)
Slow start
B)
Congestion avoidance
C)
Congestion detection
D)
none of these
উত্তর:-
Slow start
বিবরণ:-1. Slow Start Phase: Starts slow increment is exponential to the threshold.
2. Congestion Avoidance Phase: After reaching the threshold increment is by 1.
Congestion Detection Phase: The sender goes back to the Slow start phase or the Congestion avoidance phase.
6)
UDP is
A)
connection oriented
B)
connection less
C)
both A) and B)
D)
none of these
উত্তর:-
connection less
বিবরণ:-
7)
Port number is
A)
process number
B)
computer physical address
C)
both A) and B)
D)
none of these
উত্তর:-
process number
বিবরণ:-
8)
Error detection and correction at the data link level is achieved by
A)
bit stuffing
B)
cyclic redundancy codes
C)
Hamming codes
D)
Equalization
উত্তর:-
Hamming codes
বিবরণ:-
9)
IPv6 addresses are …………………bytes long.
A)
6
B)
16
C)
32
D)
128
10)
IP address in the B class is given by
A)
125.123.123.2
B)
192.023.21.54
C)
191.128.32.56
D)
10.14.12.34
উত্তর:-
192.023.21.54
বিবরণ:-
11)
Hamming code is a method of
A)
error detection
B)
error-correction
C)
error-encapsulation
D)
both A) & B)
উত্তর:-
both A) & B)
বিবরণ:-
12)
Flow control is the responsibility of
A)
Data link layer
B)
Transport layer
C)
Both A) and B)
D)
Application layer
উত্তর:-
Both A) and B)
বিবরণ:-
13)
Which channel access method is used in Ethernet networks?
A)
Pure ALOHA
B)
CSMA/CD
C)
CSMA/CA
D)
Slotted ALOHA
14)
Pure ALOHA has a maximum efficiency of
A)
18%
B)
37%
C)
10%
D)
none of these
উত্তর:-
18%
বিবরণ:-Efficiency of Pure Aloha (η) = G x e-2G
For maximum efficiency, Maximum value of η occurs at G = ½
Maximum efficiency of Pure Aloha
= 1/2 x e-2 x 1/2
= 1 / 2e
= 0.184
= 18.4%
15)
Total bandwidth required for AM is
A)
zero
B)
2 ( 1 + d ) B
C)
2B
D)
none of these
16)
At which layer circuit switching takes place?
A)
Transport layer
B)
Data link layer
C)
Physical layer
D)
None of these
উত্তর:-
Physical layer
বিবরণ:-
17)
In selective repeat sliding window protocol, the receiver window size is
A)
greater than one
B)
one
C)
two
D)
none of these
উত্তর:-
greater than one
বিবরণ:-
18)
HDLC protocols insert a 0 bit after .................. consecutive 1 bits in the message data.
A)
5
B)
7
C)
4
D)
8
19)
ICMP resides at the same layer as which of the following protocols mentioned below?
A)
TCP
B)
UDP
C)
IP
D)
ARP
উত্তর:-
IP
বিবরণ:-The ICMP stands for Internet Control Message Protocol. It is a network layer protocol. It is used for error handling in the network layer, and it is primarily used on network devices such as routers.
20)
What network topology implements at least two paths to and from each node?
A)
Bus
B)
Ring
C)
Mesh
D)
Star
