RS-449/442-A/423-A is

A. a set of physical layer standards developed by EIA and intended to replace RS-232-C.
B. a check bit appended to an array of binary digits to make the sum of the all the binary digits
C. a code in which each expression conforms to specific rules of construction, so that if certain errors occur in an expression the resulting expression will not conform to the rules of construction and thus the presence of the errors is detected
D. the ratio of the number of data units in error to the total number of data units
E. None of the above


Which of the following digits are known as the area code of the Network User Address (NUA)?

A. 5-7
B. 1-4
C. 8-12
D. 13-14
E. None of the above


End-to-end connectivity is provided from host-to-host in:

A. Network layer
B. Session layer
C. Data link layer
D. Transport layer
E. None of the above


A form of modulation In which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal, is known as

A. Aloha
B. Angle modulation
C. Amplitude modulation
D. modem
E. None of the above


CSMA (Carrier Sense Multiple Access) is

A. a method of determining which device has access to the transmission medium at any time
B. a method access control technique for multiple-access transmission media.
C. a very common bit-oriented data link protocol issued by ISO.
D. network access standard for connecting stations to a circuit-switched network
E. None of the above