Home / server / Questions / 139155
Accepted
Marco Demaio
Asked: 2010-05-07 02:34:08 +0800 CST

DNS PTR record when domain on shared IP address

  • 772

I own a typical shared IP hosting plan and domain. I can modify the DNS of the domain from the control panel. The mailserver shares the same IP address, so my typical DNS config is:

www.mydomain.com   A      -> myIP
mydomain.com       A      -> myIP
ftp.mydomain.com   A      -> myIP
mail.mydomain.com  A      -> myIP
mydomain.com       MX(10) -> myIP

I read some Q&A on this site where they suggest to add PTR record mainly for mailserver.

I would like to add PTR record to my domain, I have got two questions:

1) can PTR record be added even if the hosting/mailserver are on a shared IP address? Or do I need a dedicated IP.

2) How do I setup PTR record, I mean does it look like A record:

mydomain.com (PTR) -> myIP
domain-name-system reverse-dns dedicated-server shared-hosting ptr-record

3 Answers

  1. You can only set up a PTR record if you are the delegated maintainer of the relevant portion of the in-addr.arpa. domain name.

    In your case that would be your web host. If you have a dedicated IP address then they should allow you to request the appropriate entry. On the other hand, if you have a shared IP address then it's very unlikely that they would permit this.

    For what it's worth, if your mail server is called mail.example.com and its IP address is w.x.y.z then the appropriate DNS record would look like:

    z.y.x.w.in-addr.arpa. IN PTR mail.example.com.
    • 4
  2. Best Answer

    You can't create a PTR record for the ip address in your domain name DNS zone. The PTR record needs to be created in the rDNS zone by the owner of the netblock that encompasses your ip address. You'll need to speak to whomever you get the ip address from and ask them to create a PTR record for you.

    • 3

  3. PTR should be the server name, which also should have an IN A entry. Whether PTR can be added is TOTALLY up to the host -whether he allows you to or not. THat said, SMTP without matching PTR is kind of stupid (you get LOTS of rejects).

    How you set that up - well, dont ask here... ask you host. Because the host can tell you how o set it up ON HIS CONTROL PANEL ;)

    • 0