The forward lookup zone resolves (translates) computer names to i.p. addresses.
The reverse lookup zone resolves i.p. addresses to computer names.
Reverse lookup zones are needed for some applications.
If you send email over the internet, you will need a reverse lookup record for your mail server. In order to detect spam, many mail servers will check to see if the i.p. address from which mail is being sent, corresponds to the email address from which the mail is being sent.
If you send mail from firstname.lastname@example.org
, these mail servers will want to verify that the i.p. address on the email resolves to piyusharora420.com.
If the i.p. address does not match the domain name, or if it cannot be verified, they will reject the mail.
There may be other applications that need to do reverse lookups.
If you are running on a local area network, a reverse lookup zone may
not be necessary. For example, Windows DNS does not create a reverse lookup zone by default.
Why do you want to delete the reverse lookup zone? It doesn't hurt to have it.