problem1. The information to be transferred in data communications system is the ______.
(a) Message
(b) Protocol
(c) Medium
(d) Transmission
problem2. Which topology needs a multi-point connection?
(a) Star
(b) Mesh
(c) Ring
(d) Bus
problem3. Data flow between two devices can take place in a _______ way.
(a) Full-duplex
(b) Half-duplex
(c) Simplex
(d) All of the above
problem4. As data moves from the lower to the upper OSI layers, headers are _______.
(a) Modified
(b) Rearranged
(c) Added
(d) Removed
problem5. The physical layer is concerned with movement of __ over the physical medium.
(a) Programs
(b) Protocols
(c) Bits
(d) Dialogues
problem6. ________ is a kind of transmission impairment in which the signal loses strength due to the dissimilar propagation speeds of each frequency that makes up the signal.
(a) Crosstalk
(b) Thermal Noise
(c) Distortion
(d) Impulse Noise
problem7. In asynchronous transmission, the gap time between bytes is _______.
(a) Variable
(b) Fixed
(c) A function of data rate
(d) Zero
problem8. _______ encoding has a transition at the middle of each bit.
(a) Manchester
(b) RZ group
(c) Differential Manchester
(d) All of above
problem9. The maximum data rate over a 2 MHz channel with SNR of 20 dB is _____.
(a) 3.33 Mbps
(b) 2.16 Mbps
(c) 6.66 Mbps
(d) 13.32 Mbps
problem10. ASK, PSK, FSK are instances of ________ conversion.
(a) Digital-to-digital
(b) Digital-to-analog
(c) Analog-to-digital
(d) Analog-to-analog
problem11. Quadrature amplitude modulation (QAM) is combination of _________.
(a) ASK and FSK
(b) ASK and PSK
(c) PSK and FSK
(d) None of the above
problem12. Which multiplexing method transmits digital signals?
(a) CDM
(b) FDM
(c) TDM
(d) None of the above
problem13. A parabolic dish antenna is a (n) _______ antenna.
(a) Unidirectional
(b) Omni-directional
(c) Bi-directional
(d) Horn
problem14. In cyclic redundancy checking, the divisor is _______ the CRC.
(a) One bit more
(b) One bit less
(c) The same size as
(d) Two bits less
problem15. The most used method to convert analog data to a digital signal is called _____.
(a) PCM
(b) Sampling
(c) PAM
(d) Shift-keying