21.
Which of the following is not a characteristic of the hub architecture of Arc net?
Answer: Option 'B'
Alternative routing
22.
A group of packets from a source through an X.25 packet system to sink.
Answer: Option 'C'
arrive in the same order sent for both VC and PVC
23.
How many OSI layers are covered in the X.25 standard?
Answer: Option 'A'
four
24.
A protocol is a rule governing a time sequence of events that must take place.
Answer: Option 'A'
between peers
25.
What is the number of separate protocol layers at the serial interface gateway specified by the X.25 standard?
Answer: Option 'B'
3
26.
Layer one of the OSI model is _______.
Answer: Option 'A'
physical layer
27.
Establishing a virtual connection is functionally equivalent to _______.
Answer: Option 'C'
placing a telephone call prior to a conversation
28.
What is the main purpose of a data link content monitor?
Answer: Option 'D'
Detect problems in protocols.
29.
Protocol converters are _______.
Answer: Option 'C'
usually not operated in pairs
30.
Satellite transponders contain ______.
Answer: Option 'A'
a receiver and transmitter designed to relay microwave transmission from one point on earth to another
31.
Satellite transponders.
Answer: Option 'A'
use a higher frequency for reception of radiation from earth stations and lower frequency for transmission to earth stations.
32.
Satellite in geosynchronous orbit…
Answer: Option 'D'
remains in a fixed position so as the earth rotates it can fully cover the earth.
33.
A spin stabilized satellite.
Answer: Option 'D'
both (A) and (B)
34.
What frequency range is most affected by fog and precipitation?
Answer: Option 'C'
above 10GHz
35.
In OSI network architecture, the routing is performed by _______
Answer: Option 'B'
network layer
36.
In OSI network architecture, the dialogue control, and token management are responsibilities of _______.
Answer: Option 'D'
session layer
37.
Which of the following is not an example of data communication?
Answer: Option 'A'
A salesman telephoning orders to the office
38.
The standard ASCII ______.
Answer: Option 'B'
has 128 characters, including 32 control characters
39.
Escape sequences
Answer: Option 'A'
use ESC character to indicate the start of a special control sequence
40.
Fibre-optic cables operate at frequencies near _______.
Answer: Option 'D'
800 THz