Adding a Netblock for Reverse DNS
From Mediawiki.easydns.com
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Adding your netblock
Reverse DNS is separate from the standard DNS for a domain name, and as such is a different service. Our rate for the service is 24.95/yr per netblock (range of IP Addresses). It requires that your ISP be willing to delegate control over the netblock they have assigned you to easyDNS. Before setting up a netblock with easyDNS, please contact your ISP and ask them if they can provide you with a PTR record for your IP addresses, or, if not, if they will be able to delegate to easyDNS.
Once you have this confirmed, you will need them to provide you with the netblock itself.
We require that this be this in what is called [CIDR notation.]
This will be a numeric representation of the range with consists of the starting IP, and then the class of block-sizes, to determine theending IP of the range.
For example, if your ISP has provided you with a range of 32 IP addresses that begin at 192.1.2.0, then this is called a /27 range, and the CIDR notation for it would be 192.168.2.0/27
Once you have this in hand, log into your easyDNS account, and then go to our reverse DNS page.
Enter the CIDR block as provided, and click 
Select the Reverse DNS service level, and then click 
to generate the invoice. Click to accept our terms and conditions, then select the method of payment you prefer. Once paid, the zone will become active on our system, and once you configure it, your ISP can then delegate the block to us.
Delegation Methods (Info for your ISP)
When the reverse block is added, our system will automatically detect the current relegation method your ISP has selected, and advise you as to that you need them to do. This information is available in the Domain Administration section of your users page, in the DNS Settings tab on the Reverse Information line, behind the behind the Get Info and Change links.
If your ISP is at all uncertain about how to do this, please ask them to see [the documentation here.]
Setting up your PTR Records
Once the netblock has been added and the invoice paid, you can configure PTR records by clicking into the DNS Information line for the netblock and clicking PTR. In general, the only IPs that require PTR records are those which are the location of a sending mail server.
The first time you open this, you will see that no PTR records have been defined.
Click on 
to begin entering records for your netblock.
In this example, we imagine a sending mail server named mail.easydnstest.ca, which is located at the IP address 192.1.2.11. An A record exists in the DNS for the host mail.easydnstest.ca that points to 192.1.2.11, now we enter a PTR record for the IP address that resolves the same name. This way, when a mail server receives a message delivered by that host, it will be able to check the IP DNS and see that it agrees that this is the proper host for that address.
On the left hand side, enter the final octet of the address you want the record for. On the right, the host record you wish it to show as valid for that IP.
Once any records have been entered or edited, click 
then 
to commit the changes (if any).
After that, when you enter the PTR records for the block, you will see something like this :
What Does it all Look Like
In short, when you send mail outbound from a server, the receiving mail server may wish to check that this connecting mail server is coming from somewhere that has some sort of verification as to its identity.
So it will do lookups first on the name of the host connecting to see what the DNS for that host resolves to, and then for the PTR record to confirm they match, like so:
inboundmailserver$ dig +short mailout.easydns.com 64.68.200.141 inboundmailserver$ dig +short -x 64.68.200.141 mailout.easydns.com.
It sees they match, and allows the mail to pass.
