Physical layer deals with bit to bit delivery in networking. The data unit in the physical layer is bits. Process to process delivery or the port to port delivery is dealt in the transport layer. The various transmission mediums aid the physical layer in performing its functions.
Which transmission media provides the highest transmission speed in a network?
A.
Coaxial cable
B.
Twisted pair cable
C.
Optical fiber
D.
Electrical cable
Answer: Option C
Explanation:
Fiber optics is considered to have the highest transmission speed among the all mentioned above. The fiber optics transmission runs at 1000Mb/s. It is called as 1000Base-Lx whereas IEEE standard for it is 802.3z. It is popularly used for modern day network connections due to its high transmission rate.
Bits can be sent over guided and unguided media as analog signal by?
A.
Digital modulation
B.
Amplitude modulation
C.
Frequency modulation
D.
Phase modulation
Answer: Option A
Explanation:
In analog modulation, digital low frequency baseband signal (digital bit stream) is transmitted over a higher frequency. Whereas in digital modulation the only difference is that the base band signal is of discrete amplitude level. The bits are represented by only two frequency levels, one for high and one for low.
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.
Physical transport sublayer
Answer: Option A
Explanation:
The portion of physical 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. It handles which media connection the signal should be forwarded to physically.
In asynchronous serial communication the physical layer provides?
A.
Start and stop signalling
B.
Flow control
C.
Both A & B
D.
None of above
Answer: Option 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. Unlike asynchronous serial communication, in synchronous serial communication a clock signal is used for communication, so the start and stop method is not really required.