# Security & Physical Layer (Multiplexing, Physical Media) Interview/Exam Question-Answer

Q.1 The sharing of a medium and its link by two or more devices is called _________.

A. Fully duplexing

B. Multiplexing

C. Micropleixng

D. Duplexing

Ans : Multiplexing

Q.2 Multiplexing is used in _______.

A. Packet switching

B. Circuit switching

C. Data switching

D. Packet & Circuit switching

Ans : Circuit switching

Q.3 Which multiplexing technique used to transmit digital signals?

A. FDM

B. TDM

C. WDM

D. FDM & WDM

Ans : TDM

Q.4 If there are n signal sources of same data rate, then the TDM link has _______ slots.

A. n

B. n/2

C. n*2

D. 2n

Ans : n

Q.5 If link transmits 4000 frames per second, and each slot has 8 bits, the transmission rate of circuit this TDM is _________.

A. 32kbps

B. 500bps

C. 500bps

D. 32bps

Ans : 32kbps

Frame rate = 4000/sec and number of bits in slot = 8

Transmission rate = (4000 * 8) bps
= 32000bps
= 32kbps

Q.6 The state when dedicated signals are idle are called __________.

A. Death period

B. Poison period

C. Silent period

D. Stop period

Ans : Silent period

Q.7 Multiplexing provides _________.

A. Efficiency

B. Privacy

C. Anti jamming

D. Both Efficiency & Privacy

Ans : Both Efficiency & Privacy

Q.8 In TDM, the transmission rate of a multiplexed path is always _______ the sum of the transmission rates of the signal sources.

A. Greater than

B. Lesser than

C. Equal to

D. Equal to or greater than

Ans : Greater than

Q.9 In TDM, slots are further divided into _________.

A. Seconds

B. Frames

C. Packets

D. Bits

Ans : Frames

Q.10 Which of this is not a guided media?

A. Fiber optical cable

B. Coaxial cable

C. Wireless LAN

D. Copper wire

Ans : Wireless LAN

Q.11 UTP is commonly used in __________.

A. DSL

B. FTTP

C. HTTP

D. None of the above

Ans : DSL

Q.12 Coaxial cable consists of _______ concentric copper conductors.

A. 1

B. 2

C. 3

D. 4

Ans : 2

Q.13 Fiber optics posses following properties __________.

A. Immune electromagnetic interference

B. Very less signal attenuation

C. Very hard to tap

D. All of the above

Ans : All of the above

Q.14 If an Optical Carrier is represented as OC-n, generally the link speed equals(in Mbps) __________.

A. n*39.8

B. n*51.8

C. 2n*51.8

D. None of the above

Ans : n*51.8

Q.15 Terrestrial radio channels are broadly classifed into _____ groups.

A. 1

B. 2

C. 3

D. 4

Ans : 3

Q.16 Radio channels are attractive medium because __________

A. Can penetrate walls

B. Connectivity can be given to mobile user

C. Can carry signals for long distance

D. All of the above

Ans : All of the above

Q.17 Geostationary satellites ___________.

A. Are placed at a fixed point above the earth

B. Rotate the earth about a fixed axis

C. Rotate the earth about a varying axis

D. All of the above

Ans : Are placed at a fixed point above the earth