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  1. #1
    Join Date
    Mar 2007
    Posts
    239

    Reverse DNS (mail setup)

    Hi guys,

    I am trying to setup reverse DNS on my server.

    I have 3 IP's. 1 main physical IP and 2 failover IP (ip aliases) that point to the main IP. I have setup mydomain.com and created the following DNS entries for it:

    mail.mydomain.com. A xx.121.xx.79
    mail.mydomain.com. A xx.23.xx.227
    mail.mydomain.com. A xx.23.xx.228

    Questions:

    1) Do i need to create 3 mail entries in the dns if I wish to run mail on each ip?

    2) How can I setup reverse DNS?

    Thanks in advance.

  2. #2
    Join Date
    Apr 2002
    Posts
    930
    What IP address or addresses are going to be sending out mail?

    Another words, if you send out an e-mail, what IP address is the recipient mail server going to see that message coming from?

    Reverse DNS should work such that an IP address (aa.bb.cc.dd) resolves to a hostname (host.name.com) and then that hostname (host.name.com) resolves back to the original IP address (aa.bb.cc.dd).

    Reverse DNS is done by whoever has delegation access to the IP zone record. Usually this is your datacenter provider.

  3. #3
    By default emails are sent out from the main IP address of the server, normally it's eth0. So in this case, you need a rDNS only for the main IP.

    If you have configured to send out emails from each of your IP (the option is provided on cPanel servers to send out emails from the IPs that are assigned as dedicated IPs), so in this case, you will need to set rDNS for each of the IP.

    Make sure the hostname should be pointing to the main IP address of the server as that is the IP from where the emails are sent by default. The IP should point back to the hostname in order for the emails to work properly.

    BTW, rDNS is normally set by the Data Center ppl, so contact your hosting company.
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  4. #4
    Join Date
    Mar 2007
    Posts
    239
    Quote Originally Posted by madaboutlinux View Post
    By default emails are sent out from the main IP address of the server, normally it's eth0. So in this case, you need a rDNS only for the main IP.

    If you have configured to send out emails from each of your IP (the option is provided on cPanel servers to send out emails from the IPs that are assigned as dedicated IPs), so in this case, you will need to set rDNS for each of the IP.

    Make sure the hostname should be pointing to the main IP address of the server as that is the IP from where the emails are sent by default. The IP should point back to the hostname in order for the emails to work properly.

    BTW, rDNS is normally set by the Data Center ppl, so contact your hosting company.
    Thanks, I managed to get it working :-)

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