正Man's World

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1.

Network administrators use the tool,traceroute,to test to see whether the remote computer is currently online.

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2.

In Client-Server Computing,the program that waits for contact is called a client and the program that initiatescontact is known as a server.

( O )

3.

Physically,the antennas used with RF networks may be large or small、depending on the range desired.

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4.

On the standard 25-pin connector、a cable used to connect 2 computers(2 DCE devices) must have a wire from pin 2 to pin 3 and a wire from pin 3 to pin 2.

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5.

The RS-232 standard specifies that a receiver should measure the voltage exactly at the beginning of each bit.

Some companies configure their site to rehect ping packets.The motivation for disabling ping is for

(a) routing (b) productivity (c) efficiency (d) security (e) cost reason

Many operating systems include a function named

(a) choose (b) select (c) connect (d) pick (e) alternate

that solves the problem of managing multiple connections.

Conventional computer networks use copper wires as the primary medium to connect computers because the following reasons except

(a) wire is inexpensive (b) easy to install
(c) its low resistance to electric current
(d) less electrical interference (e) signals can travel farther.

All of the following statements about geosynchronous satellite are true,except

(a) also known as geostationary satellite.
(b) is placed in an orbit that is exactly synchronized with the rotation of the earth.
(c) such an orbit is classified as a Geostationary Earth Orbit(GEO).
(d) the distance required for geosynchronous orbit is 400 miles.
(e) Engineers sometimes refer to the distance as high earth orbit.

Satllites in lower orbits rotate

(a) faster than (b) same speed as (c) slower than (d) randomly (e)don't know

the rotation of the earth.

How many low earth orbit satellites are required to provide service over the entire surface of the earth?

(a) 45 (b) 56 (c) 66 (d) 76 (e) 90

The RS-232C standard was produced by the

(a) International Telecommunications Union (ITU)
(b) Electronic Industries Association (EIA)
(c) Institute for Electrical and Electronic Engineers (IEEE)
(d) National Institute of Standards and Technology (NIST)
(e) National Bureau of Standards (NBS)

In addition to control wires、full duplex transmission in RS-232 requires

(a)1 (b) 2 (c) 3 (d) 4 (e) 5

wires for sending data.

Usually、the signdal-to-noise,S/N、is not represented directly、engineers measure in decibels (dB) by the quantity of

(a) 10log₁₀S/N (b) 10log₂S/N (c) 2log₁₀S/N (d) 2log₂S/N
(e) none of the above.

What id Domain Name System (DNS)?

List 3 types of basic wires that networks use to minimize interference?

Why does the communication company launch a set of satellites(satellite arraus) into low earth orbits?(list 2 reasons)

Explain the reason why RS-232 standard requires to transmit an extra start bit(1 or 0) before transmitting the bits of a character?

Explain the reason why RS-232 standard requires to transmit an extra start bit(1 or 0) appended to each character?

Using the Nyquist Intersymbol Interference Theorem to explain why the maximum data rate of RS-232 can be achieved over a transmission system of bandwidth B is 2B. (List Nyquist's theorem and explain)