21. Bus is
A. one or more conductors that some as a common connection for a related group of devices
B. a continuous frequency capable of being modulated or impressed with a second signal
C. the condition when two or more stations attempt to use the same channel at the same time
D. a collection of interconnected functional units that provides a data communications service among stations attached to the network
E. None of the above
22. Which of the following medium is used for broadband local networks?
A. Coaxial cable
B. optic fiber
C. CATV
D. UTP
E. None of the above
23. In cyclic redundancy checking what is the CRC?
A. the divisor
B. the quotient
C. the dividend
D. the remainder
24. What is the maximum number of entries in the HOSTS file?
A. 8
B. 255
C. 500
D. Unlimited
E. None of the above
25. The communication mode that supports data in both directions at the same time is
A. simplex
B. half-duplex
C. full-duplex
D. multiplex
E. None of the above