How to Create Network Solutions for Reverse DNSby Drew Nelson
DNS stands for domain name system. DNS translates domain names into IP addresses and reverse DNS translates IP addresses into domain names. This is necessary because computers use IP addresses while people use readable names. Forward DNS is set up through your domain registrar. Reverse DNS is set up through your internet service provider (ISP). Without reverse DNS, some internet and e-mail functions will not work. Often reverse DNS is neglected when setting up a network.
Find out if your ISP (internet service provider) will delegate DNS look up to your servers. If yes, then you can handle reverse DNS yourself. Check out the documentation for the DNS server you are using for more details.
Rely on the ISP to provide and support reverse DNS services if the ISP will not delegate DNS look up to your servers. In this situation you must provide the ISP with the necessary information to create the reverse DNS zone on its servers (see Step 4).
Set up the reverse DNS entries on the DNS servers. No matter who provides the service, the reverse DNS entries must be made. Reverse DNS entries consist of a host name with a reversed IP address with ".in-addr.arpa" added to the end.
Provide the ISP with information pertaining to the domains and IP addresses of the reverse DNS servers. No matter who provides the reverse DNS service, you need to make sure the ISP provider knows where your DNS servers are located so they can add this information to the root servers.
- If you do not provide the ISP with the domains and IP addresses of the reverse DNS servers, no one will be able to get to your DNS servers even with correct reverse DNS entries.
- Reverse DNS allows a receiving mail server to verify that the party sending e-mail actually exists at that domain and with the IP address claimed. This verification process is done to keep spam e-mail from getting through.
- Mail servers with no reverse DNS will have a hard time getting e-mail to certain large ISPs because these ISPs will be unable to verify the email.