Domain Name System - Quiz Explanation
The answers you selected are indicated below, along with text that explains the correct answers.
1.
What is the purpose of the Domain Name System (DNS)?
Please select the best answer.
A.
To dictate the Internet's network arrangement
B.
To map port names to port numbers
C.
To map host names to IP addresses
D.
To register names on the Internet
The correct answer is C.
The Domain Name System maps host names to IP addresses. Answer A is incorrect because no one (not even DNS) has the influence or capability to dictate the Internet's arrangement. Answer B is incorrect because Linux internally maps port names to port numbers. Answer D is incorrect because name registration is the responsibility of Internet registrars, such as NIC.
2.
In a fully qualified domain name, what does the name before the first dot represent?
Please select the best answer.
A.
The host's network
B.
The host's name
C.
The top-level domain
D.
The domain's network
The correct answer is B.
The names between the first dot and last declare the network. Answer A is incorrect because the host's name, which is specific on a given network, must come before the first dot. Answer C is incorrect because the top-level domain is specified last in a FQDN. Answer D is incorrect because domains do not have networks.
3.
What is the minimum number of fields in the port name to number mapping file?
Please select the best answer.
A.
1
B.
2
C.
3
D.
4
The correct answer is B.
Linux expects valid entries in
/etc/services
to contain at least a primary port name and number, so only answer B is correct.
4.
What ports has the IANA declared reserved?
Please select the best answer.
A.
0 through 1023
B.
1 through 1024
C.
0 through 1024
D.
1 through 1023
The correct answer is D.
IANA reserves ports 1 through 1023. Answers A and C are incorrect because the first reserved port is 1. Answer B is incorrect because the last reserved port is 1023.
