1

I have a VPS with the following IP: 82.197.45.124

domain: example.com
hostname: server.example.com
PTR record: 82.197.45.124 > server.example.com

There is no an "A" record for "server"

mood@desk:~$ host 82.197.45.124
124.45.197.82.in-addr.arpa domain name pointer **server.example.com**

mood@desk:~$ host **example.com**
example.com has address 82.197.45.124
example.com mail is handled by 10 mail.example.com.

They say that DNS lookup must match reverse DNS lookup.

But as you can see there are no exact match; server.example.com != example.com

Must I change the PTR record like 82.197.45.124 > example.com?

Is this a good RDNS record or not?

If not, what is the correct RDNS (PTR) record for a mail server?

7

The domain name in the email address is fairly irrelevant. The name used in the MX record doesn't really matter either. ISPs will often use something like mail.customer-domain.com in MX records, all pointing to one server whose real name is obviously not mail.customer-domain.com. What does matter is the servers actual hostname.

When talking via SMTP, your server will identify itself in the SMTP conversation using its full hostname, in this case 'server.example.com'.

The A record for 'server.example.com' should point to the IP of your server, and the PTR record for this IP address should match the hostname.

server.example.com. A 82.197.45.124

124.45.197.82.in-addr.arpa. PTR server.example.com
  • shortly, I have to add an "A" record for "server" pointing 82.197.45.124... And that's all, isn't it? – thomas May 24 '13 at 20:32
  • I've updated the answer to include sample DNS entries. You should have an A record for the hostname pointing at your server, and a PTR for the IP which contains the server hostname. The PTR will probably need to be set up by the ISP that own your IP address. (Looking back at your question it looks like the correct PTR is already set up, so yes, just set up the A record and you should be set up correctly) – USD Matt May 24 '13 at 20:35
  • dear Matt, Thank you very much for this great answer. it is very helpful... :) – thomas May 24 '13 at 20:42
-1

PTR can be anything, normally people tend to use hostname of the server / VPS tough. If you check any other domain such as "serverfault.com" for example or "ebay.com" with this tool (link just below) or any other similair tool, you will see the PTR doesn't really follow any pattern :)

http://www.intodns.com/serverfault.com

  • thank you, this site is good tool for checking dns records... – thomas May 24 '13 at 20:44
  • 1
    On a mail server the PTR can't be anything, you'll get problems with quite a few ISPs (especially the big ones) rejecting your mail if it doesn't match the hostname used in SMTP communications. They'll also check the A record of the hostname your mail server claims to be against the IP your server is connecting from. – USD Matt May 24 '13 at 20:44
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    PTR record = anything -> mail to spam folder. If you are connecting to my mail servers it also means several delays in delivering email. For non mail servers PTR records aren't important. Many ISPs use names which are indicative of infrastructure for dynamic addresses. Often they don't have corresponding A records, and helps identify addresses which should not be sending email directly. – BillThor May 25 '13 at 2:54

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