A reverse DNS (rDNS) is used to determine a domain from an IP address. It is commonly used as an anti-SPAM measure to determine if a domain has been mapped to the IP address from which the email originates, mail servers (MTA's) if configured to do so will refuse to accept email from a downstream mail server if it's IP address cannot be resolved to a domain.
Setting up a rDNS record is relatively straight forward but it can only be done by a delegate authority of the IP address range in which the IP address resides. To set up a rDNS you will need to contact the provider of your IP address which is more than likely to be your connection provider ISP.
Article ID: 2, Created On: 11/9/2011, Modified: 11/9/2011