Archive for April 4, 2007

Question 54

Which of the following is the appropriate characteristics of connectionless communication ?

a) A connection called PVC is always adopted. A communication path with the counterpart is established in advance, so communication can be done without prior arrangement for connection.
b) All of the data units to be transmitted pass through the same router
c) All packets to be transmitted contain information indicating the destination.
d) Reliability is high because sequence error detection and flow control are carried out.

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Question 53

Which of the following standards is used to attach image data to e-mails in an environment that uses TCP/IP?

a) JPEG
b) MIME
c) MPEG
d) SMTP

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Question 52

Which of the following techniques allows multiple LAN terminals using private addresses to access the Internet by sharing a single global address by means of identifying the TCP and UDP port numbers and managing the correspondence between the private addresses and the global address?

a) IP masquerading
b) IP multicasing
c) IP spoofing
d) NTP3

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Question 51

The figure shows the route used when a client on the TCP/IP network within an organization accesses a Web server outside the organization via a proxy server, a router, and the Internet. Where are the TCP connections for this communication established?

2007-04-q51.png

a) Between the client and the proxy server and between the proxy server and the Web server.

b) Between the client and the proxy server, between the proxy server and the router, and between the router and the Web server.

c) Between the client and the router and between the router and the Web server.

d) Between the client and the Web server and between the client and the proxy server.

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Question 50

An effort was made to reduce communication network costs by introducing multiplexers (the. marks in the figure below) to a communication network that directly connects the headquarters with each branch office. What is the cost reduction per month in US$? Here, the monthly line costs (US$) between branches for the old and new networks are as shown in the figure below. In addition, two multiplexers were introduced under a lease contract at a monthly fee of 2% of the unit cost of US$30,000 each. The costs for modems and other communication devices can be ignored.

2007-04-q50.png

a) 1,000
b) 1,300
c) 1,500
d) 1,900

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Question 49

There is a database in which operations such as adding, updating, and deleting data occur at a low but constant level of frequency. The database is backed up to magnetic tapes. When the backup interval is double from the current interval, which the following is an appropriate statement regarding the database operation?

a) The amount the database approximately doubles.
b) The average execution time of each backup operation approximately doubles.
c) The average recovery time from the journal information approximately doubles.
d) The number of magnetic tapes used per backup is reduced approximately half.

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