Create a reverse DNS record

Reverse Domain Name Service (DNS) records are essential for those running a
mail server because many recipient servers reject, or mark as spam, all email
that originates from an unauthenticated server.

This means that after the sending IP address is checked, if the reverse
DNS does not match the sending domain, then it is classed as
"unauthenticated".

Having a Reverse DNS record
attached to your domain does not automatically guarantee acceptance of
email originating from your domain by the recipient's email server. It's
just that non-matching or generic reverse DNS lookup settings are often
rejected out of hand. Having a reverse DNS record for your domain will
prevent email originating from your domain from getting immediately
rejected.

RDNS can also be very useful when tracking down network issues and was
the original driving force of RDNS. When pinging a website or IP
address, one part of the output is the server's RDNS record.

When you enter a domain name into your browser, the DNS system finds
the IP address of the server the domain is associated with.

A reverse DNS lookup does the opposite. It establishes what domain is
associated with the IP address. This is a useful setting to configure and
is essential for customers who run an outgoing mail server on their
Cloud Server.

This article shows you how to add a reverse DNS record (also known
as an RDNS record and a PTR record) to map your server's IP address to a
domain name (for example, 1.2.3.4. to example.com) in the Cloud Control Panel.

Create a reverse DNS record

Perform the following steps the create a reverse DNS record in the Cloud Control Panel:

1. Log in to the Cloud Control Panel.

2. In the top navigation bar, click Select a Product > Rackspace Cloud.

3. Select Servers, then click the link for your Cloud Server from your
   Servers List.

4. On the Server Details screen, click Add Record next to the
   Reverse DNS.

5. In the Add Record pop-up window:

   • Enter your domain name (for example mail.example.com) in the
     Hostname field.
   • Set the Time to Live (TTL) for the record.
   • Click Save Record.

6. Back at the Server Details screen, one record now displays
   next to Reverse DNS. Click this link to display the details for the
   reverse DNS that you just added.