You work as the network administrator at Domain.com. The Domain.com network consists of a single Active Directory domain named Domain.com. Domain.com has its headquarters located in London and branch office located in Paris. All servers on the Domain.com network run Windows Server 2008 and all client computers run Windows Vista.
During the course of the day whilst performing routine maintenance you discovered that a spammer tried sending junk mail via an unwary mail server at Domain.com. You have additionally determined that the spammer used a fake DNS name which they assumed would be accepted by the mail server but is still rejected. Domain.com has later asked you what caused to mail server to refuse the spammer’s mail.
What would your reply be?

A.
You should inform Domain.com that the mail is rejected when a mail server doing a reverse lookup zone with the aim of confirming that DNS names are not fake.

B.
You should inform Domain.com that the mail is rejected when the spammer has no MX record in the database of the DNS server which serves the mail server’s domain.

C.
You should inform Domain.com that the mail is rejected when the spammer’s DNS name is not found in the cache file of the primary DNS server serving the mail server’s domain.

D.
You should inform Domain.com that the mail is rejected when a fake DNS name is detected.

Explanation:

The majority of mail servers are capable of being configured to have incoming mail rejected from servers whose IP addresses cannot be determined with a reverse lookup.