Computer Networks Questions & Answers – Physical Layer
1. The physical layer concerns with
a) bit-by-bit delivery
p) process to process delivery
c) application to application delivery
d) none of the mentioned
a) bit-by-bit delivery
p) process to process delivery
c) application to application delivery
d) none of the mentioned
Answer: a
Explanation: Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery is dealy in the transport layer.
Explanation: Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery is dealy in the transport layer.
2. Which transmission media has the
highest transmission speed in a network?
a) coaxial cable
b) twisted pair cable
c) optical fiber
d) electrical cable
a) coaxial cable
b) twisted pair cable
c) optical fiber
d) electrical cable
Answer: c
Explanation: Fibre optics is considered to have the highest transmission speed among the all mentioned above. The fibre optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE stndard for it is 802.3z.
Explanation: Fibre optics is considered to have the highest transmission speed among the all mentioned above. The fibre optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE stndard for it is 802.3z.
3. Bits can be send over guided and
unguided media as analog signal by
a) digital modulation
b) amplitude modulation
c) frequency modulation
d) phase modulation
a) digital modulation
b) amplitude modulation
c) frequency modulation
d) phase modulation
Answer: a
Explanation: In analog modulation, digital low frequency baseband signal (digital bitstream) are transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level.
Explanation: In analog modulation, digital low frequency baseband signal (digital bitstream) are transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level.
4. The portion of physical layer
that interfaces with the media access control sublayer is called
a) physical signalling sublayer
b) physical data sublayer
c) physical address sublayer
d) none of the mentioned
a) physical signalling sublayer
b) physical data sublayer
c) physical address sublayer
d) none of the mentioned
Answer: a
Explanation: The portion of physcial layer that interfaces with the medium access control sublayer is Physical Signaling Sublayer. The main function of this layer is character encoding, reception, decoding and performs optional isolation functions.
Explanation: The portion of physcial layer that interfaces with the medium access control sublayer is Physical Signaling Sublayer. The main function of this layer is character encoding, reception, decoding and performs optional isolation functions.
5. physical layer provides
a) mechanical specifications of electrical connectors and cables
b) electrical specification of transmission line signal level
c) specification for IR over optical fiber
d) all of the mentioned
a) mechanical specifications of electrical connectors and cables
b) electrical specification of transmission line signal level
c) specification for IR over optical fiber
d) all of the mentioned
Answer: d
Explanation: Anything dealing with a network cable or the standards in use – including pins, connectors and the electric current used is dealt in the physical layer (Layer 1).
Explanation: Anything dealing with a network cable or the standards in use – including pins, connectors and the electric current used is dealt in the physical layer (Layer 1).
6. In asynchronous serial
communication the physical layer provides
a) start and stop signalling
b) flow control
c) both start & stop signalling and flow control
d) none of the mentioned
a) start and stop signalling
b) flow control
c) both start & stop signalling and flow control
d) none of the mentioned
Answer: c
Explanation: In asynchronous serial communication, the communication is not synchronized by clock signal. Instead of a start and stop signaling and flow control method is followed.
Explanation: In asynchronous serial communication, the communication is not synchronized by clock signal. Instead of a start and stop signaling and flow control method is followed.
7. The physical layer is responsible
for
a) line coding
b) channel coding
c) modulation
d) all of the mentioned
a) line coding
b) channel coding
c) modulation
d) all of the mentioned
Answer: d
Explanation: The physical layer is responsible for line coding, channel coding and modulation that is needed for the transmission of the information.
Explanation: The physical layer is responsible for line coding, channel coding and modulation that is needed for the transmission of the information.
8. The physical layer translates
logical communication requests from the ______ into hardware specific
operations.
a) data link layer
b) network layer
c) trasnport layer
d) application layer
a) data link layer
b) network layer
c) trasnport layer
d) application layer
Answer: a
Explanation: Physical layer accepts data or information from the data link layer and converts it into hardware specific operations so as to transfer the message through physical cables.
Explanation: Physical layer accepts data or information from the data link layer and converts it into hardware specific operations so as to transfer the message through physical cables.
9. A single channel is shared by
multiple signals by
a) analog modulation
b) digital modulation
c) multiplexing
d) none of the mentioned
a) analog modulation
b) digital modulation
c) multiplexing
d) none of the mentioned
Answer: c
Explanation: In communication and computer networks, the main goal is to share a scarce resource. This is done by multiplexing, where multiple analog or digital signals are combined into one signal over a shared medium.
Explanation: In communication and computer networks, the main goal is to share a scarce resource. This is done by multiplexing, where multiple analog or digital signals are combined into one signal over a shared medium.
10. Wireless transmission can be
done via
a) radio waves
b) microwaves
c) infrared
d) all of the mentioned
a) radio waves
b) microwaves
c) infrared
d) all of the mentioned
Answer: d
Explanation: Wireless transmission is carried out by radio waves, microwaves and IR waves. These waves range from 3 Khz to above 300 Ghz and are more suitable for wireless transmission because they allow a wider band for modulating signals, so you can obtain higher frequency transmission.
Explanation: Wireless transmission is carried out by radio waves, microwaves and IR waves. These waves range from 3 Khz to above 300 Ghz and are more suitable for wireless transmission because they allow a wider band for modulating signals, so you can obtain higher frequency transmission.
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