DNS maps domain names to IP addresses (d). Packet filtering firewalls allow only packets with specific TCP port numbers through to the internal network (d). Setting an upper limit on each user's mailbox capacity avoids a shortage of total mailbox capacity at the mail server (a).

1. Network
by Tanat Tonguthaisri
itpe@nstda.or.th

2. 1. Which of the following is the role of
DNS in a TCP/IP network?
a) It allocates an unused IP address from the
addresses registered in a server in response to
an IP address allocation request from devices
such as PCs.
b) It allows server programs to be called by
specifying only the program name, regardless
of the server IP address.
c) It translates an in-house private IP address to a
global IP address to enable access to the
Internet.
d) It maps a domain name or a host name to an IP
address.

3. 2. Which of the following can be implemented
by using the packet filtering of a firewall?
a) Tampered packets received from the Internet are
corrected. If a packet cannot be corrected, a log is
generated and it is blocked from passing into the internal
network.
b) The header and data of the packet received from the
Internet are checked for tampering. If any tampering is
detected, the packet is discarded.
c) A packet with a dynamically allocated TCP port number is
permitted to pass through to the internal network by
converting the packet to one with a fixed TCP port number
on the receiver side.
d) Only packets with a specific TCP port number are
permitted to pass through to the internal network from the
Internet.

4. 3. Which of the following is an appropriate
measure to avoid a shortage of total mailbox
capacity at the mail server?
a) Setting an upper limit for each
user’s mailbox capacity
b) Implementing mirrored disks on the
mail server
c) Having back-ups of mail data
d) Sending large e-mails in bulk during
hours when they do not adversely
affect the transmission of other e-mails

5. 4. Which of the following is an appropriate
description concerning protocols and
languages related to the Internet?
a)FTP is a protocol for transferring e-mail
messages with files attached to them.
b)HTML is a language that allows the user to
define tags for describing the logical
structure of a document.
c) HTTP is a protocol for transferring
information such as HTML documents.
d)SMTP is a protocol for sending and
receiving image information.

6. 5. Which of the following is an appropriate
description of DNS?
a) It is a system used for searching a wide variety
of information on the Internet.
b) It is a system used for mapping between host
names and IP addresses of devices connected
to the Internet.
c) It is a personal authentication system used
for providing a safe and secure online shopping
environment.
d) It is a system used for managing personal e-
mail addresses for e-mail delivery.

7. 6. Which of the following is the mechanism
installed between the Internet and the
internal network in order to prevent
unauthorized access via the Internet?
a) Gateway
b) WAN
c) Firewall
d) Switching hub

8. 7. Which of the following is an
appropriate description concerning a
router used in an IP network?
a)It maps domain names to IP addresses.
b)It selects the path for transmitting packets
based on IP addresses.
c) It converts analog signals to digital signals
and vice versa.
d)It executes processes and provides data
upon requests from other computers.

9. 8. Which of the following is an appropriate
description concerning the selection of
communication protocols used between a PC
and a mail server when e-mails are sent and
received between PCs?
a)PCs use POP for sending e-mails and
SMTP for receiving them.
b)PCs use SMTP for sending e-mails and
POP for receiving them.
c) PCs use POP for both sending and
receiving e-mails.
d)PCs use SMTP for both sending and
receiving e-mails.

10. 9. Which of the following is an appropriate
explanation of MIME used on the Internet?
a)It is a description language for hypertext on
the Web.
b)It is a hypertext transmission protocol
between client and server on the Internet.
c) It is a method of address notation for
uniquely identifying a resource on the
Internet.
d)It is a standard that enables e-mail to
support multimedia information such as
audio and images.

11. 10. Which of the following is the network area
that is provided by installing a firewall and is
accessible from both the Internet and the
intranet but not accessible to the intranet?
a) DHCP
b) DMZ
c) DNS
d) DoS

12. 11. A Web server in Company A provides SSL
communication using a digital certificate for the Web server
generated by a certification authority. Which of the following
is a procedure in which a PC accesses the Web server of
Company A and after obtaining a digital certificate, uses the
public key of the certification authority?
a) Generating a common key used for encrypted
communication and encrypting it by using the public key
of the certification authority
b) Using the public key of the certification authority to
decrypt the common key used for encrypted
communication
c) Using the public key of the certification authority to verify
the validity of the digital certificate
d) Encrypting confidential data by using the public key of
the certification authority

13. 12. Which of the following is an appropriate
combination of the protocols that are used for
transmitting and receiving e-mail as shown in the
diagram below? (3) Transfer e-mail
Mail server Mail server
(1) Send e-mail (2) Receive e-mail
Mail client
(1) (2) (3)
a) POP3 POP3 SMTP
b) POP3 SMTP POP3
c) SMTP POP3 SMTP
d) SMTP SMTP SMTP

14. 13. Which of the following is a
mechanism that enables a Web server to
store user information in a browser in
order to identify which PC is accessing
the Web server?
a) CGI
b) Cookie
c) SSL
d) URL

15. 14. When ten e-mail messages are sent successively
from Company A to Company B, they may arrive at
Company B in a different order from the order they are
sent. Which of the following is an appropriate opinion
on this matter?
a)There is a problem with the setup of
Company A’s mail server.
b)There is a problem with the setup of
Company B’s firewall for e-mail.
c) There is a high possibility that e-mail
delivered late is falsified on the way.
d)The arrival sequence is subject to change
because of different transfer routes.

16. 15. As shown in the figure below, a LAN system
comprises two PCs, one server, and one printer. When
PC A cannot print any output data on the printer, which
of the following should be applied to blank P in the
problem determination flowchart? Here, both PCs can
send output data directly to the printer without using the
server.
[LAN System]

17. 15.(cont.) [Flowchart]
a) PC A is not connected to the LAN system.
b) PC A has something wrong with output settings such as the
print queue.
c) The LAN system does not work because of a failure in the hub.
d) The printer does not work because of a hardware failure.

18. 16. Which of the following is an
appropriate explanation of a router that
allows messages to be sent between
two or more networks?
a) It performs connection at the data link layer, and provides
the traffic isolation function.
b) It converts protocols including protocols above the
transport layer, and interconnects networks with different
types of network architecture.
c) It performs connection at the network layer, and is used for
connecting LANs via wide-area networks.
d) It performs connection at the physical layer, and is used for
extending the connection distance.

19. 17. In order to implement communication between applications via a
network, a number of protocols are used in a hierarchical structure.
Which of the following is the appropriate combination of the protocol
names to be inserted into blanks A and B in the description below?
When a Web page is viewed via the Internet, the browser and the
Web server use a protocol called A . Communication over this
A uses a protocol of a lower layer called B and a
protocol of a further lower layer called IP (Internet Protocol).
A B
a) FTP (File Transfer Protocol) Ethernet
b) HTTP (Hyper Text Transfer Protocol) TCP (Transmission Control Protocol)
c) SMTP (Simple Mail Transfer Protocol) POP3 (Post Office Protocol version 3)
d) WWW (World Wide Web) HTML (Hyper Text Markup
Language)

20. 18. Which of the following is an appropriate
explanation concerning URL?
a) It is a communications protocol
between a Web page and a browser.
b) It is a message about the update
history of a Web page.
c)It is grammar for describing the content
(body) of a Web page.
d) It is a notation for representing the
location of a Web page.

21. 19. When an e-mail message titled “Returned
mail: Host unknown” is returned in response
to an e-mail over the Internet, which of the
following is a probable cause of this
message?
a) The recipient’s mail server remains stopped.
b) In the recipient’s address, the domain name after
the @ symbol is incorrect.
c) The transmitted data is too large, so it exceeds
the mail server’s storage capacity.
d) The encoder used for the attached file is
incompatible with the recipient’s decoder.

22. 20. Which of the following is an appropriate
description of VoIP?
a) It is a method that enables PC users to access data or
applications available on the Internet.
b) It is a technology that converts voice data into packets and
transmits them in real-time over an IP network.
c) It is a technology that ensures the security of communication
by using authentication, encryption, and decryption between
network nodes.
d) It is a system that defines and manages a correspondence
between a host name and an IP address for a network-
connected computer.

23. 21. Which of the following prevents
unauthorized external access by using packet
filtering at the connection point between a
company’s internal network and the Internet?
a) DNS
b) NAT
c) Gateway
d) Firewall

24. 22. Which of the following is an appropriate
explanation concerning the function of a
router?
a) It optically reads data such as picture and
text and then converts it into digital data.
b) It converts analog signals to digital signals
and vice versa.
c) It controls the communication path of data
and relays data across networks.
d) It archives and provides data of Web pages
by using networks.

25. 23. Which of the following is an appropriate
description concerning a cookie used in the
Web?
a) It is a standard that can be used for formatting the
layout of an HTML document in detail.
b) It is the HTTP protocol to which an encryption
function is added for private communications over the
Internet.
c) It is a mechanism where a Web server interacts with
external programs to create Web pages dynamically.
d) It is a mechanism where information from a Web
server is temporarily saved in a browser that
accesses the Web server.

26. 24. Which of the following is a system
configuration that introduces Internet
technology into a company’s information and
telecommunication system and is used for
information sharing and business support?
a) EDI
b) VAN
c) Intranet
d) Extranet