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Need help setting up reverse DNS with new ISP

Posted on 2004-10-17
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Last Modified: 2013-11-30
I just switched ISPs, and we've got a lot of our outbound emails being returned which I attribute to reverse DNS not being setup.  I need help in understanding how one sets this up(my ISP is USELESS)
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Question by:HubTechnical
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by:NetoMeter Screencasts
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Hi!
I had to go through this a few weeks ago so I think I can help you.
E-mails were rejected from mail servers which performed a reverse lookup.

If I undrestand correct you are hosting your own External DNS server and you do not have a reverse lookup zone.
There are two questions which I need the you to answer:
1.What is the OS which you are using for your DNS server?
2.What is the IP range provided by your ISP (most probably you do not have a whole C class so setting the reverse zone is a liitle bit specific).

Waiting for your answers :)

NetoMeter
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kiranghag earned 500 total points
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if you have the DSN servers in your control..
you need to make sure that the forward lookup records are setup properly...this means that the record named yourhost.com should contain proper IP address of your machines

and then also make sure that the reverse lookup zones are also proper...thease zones have names like...in-addr.arpa.xxx.yyy.zzz where zzz.yyy.xxx is the network of yours (note the order of alphabets)

here you will find entry for your host haivng address zzz.yyy.xxx.abc
you need to find this abc record and make sure that the domain name stored in this is correct.

if its a linux/unix based machine, make sure that you update the serial number in the zone config files and restart the server. most of the time people forget to update this number and then the configs are not taken by servers :-)

and if the servers are not with you, you need to make a request to the dns guys and get the records updated.

dns update can sometimes take time to propogate, so if you havent, wait for few hours before you attempt to check.

hope i m simple and clear...

:-)
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by:The--Captain
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>which I attribute to reverse DNS not being setup

It sounds like you are not sure this is the case - review the exact error message returned when the messages bounce to verify this is indeed the case (or post the bounced message here so we can verify).

>my ISP is USELESS

So, you just switched to an ISP that you consider "useless"?  Might I ask why?

In any case, it sounds like your ISP controls the authority for your in-addr.arpa zone.  If they are "useless" as you say, you may have to find a less "useless" ISP, as you are going to have to do one of two things:

1. Have them [ISP] configure PTR records for your in-addr.arpa zone (or subset thereof), or
2. Have them delegate DNS authority for your in-addr.arpa zone (or portion thereof) to your local DNS servers,
    and then configure your local servers to handle the in-addr.arpa zone PTR lookups.
 
Hope that helps.

Cheers,
-Jon
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by:PennGwyn
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Agreed.  If you have less than a Class C, you need the ISP to either set this up, or delegate it to you -- you can't make it work without them.

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by:The--Captain
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>If you have less than a Class C, you need the ISP to either set this up, or delegate it to you

Even if the network in question is a full /24, the assistance of the upstream is likely required...

Cheers,
-Jon
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