Kelli has created a DNS address entry for a server. She want users to be able to find
the server by its IP address as well. The server IP address is 197.170.33.21. Which
action should Kelli perform so that users can look up the server by its IP address?

A.
No action is required, the DNS address record will allow users to look up the IP
address as well as the host name.

B.
Assign an in-addr.arpa address of 197.170.33.21 in-addr.arpa to the server in a pointer
record in DNS.

C.
Assign a Canonical Name (CNAME) to the server in DNS.

D.
Assign an in-addr.arpa address of 33.170.197.in-addr.arpa to the server’s IP address of
21 in a pointer record in DNS.

Explanation:
In order to be able to do a reverse lookup, PTR records need to be
created. The domain zone is defined as the reverse IP address of the network, with
in-addr.arpa appended. The network for 197.170.33.21 is 197.170.33, and reversing
the order of the network gives 33.170.197.

Incorrect Answers:
A: A separate domain zone must be created for the PTR records, and this is notautomatically
created.
B: The network address must be used, and the octet order reversed.
C: The CNAME will not work in this situation. When resolving an IP address, it will beresolved to
the in-addr.arpa type of domain. It could never be resolved to a CNAME,since in order to do so,
you need to know the domain, and an IP address does not belongto nor identifies a domain.