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I need to check a reverse PTR record to make sure that a script I have is sending emails which will actually received by my users and not incorrectly marked as spam.

I understand that the ISP which owns the IP range has to set up the PTR record, but how do I check if it is already set up?

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2 Answers

up vote 12 down vote accepted

If you have unix or linux, you can do this by typing on a command prompt:

dig -x xx.yy.zz.aa

You'll get an answer with your authority of aa.zz.yy.xx.in-addr.arpa and server resolving to this address.

In windows you can do nslookup xx.yy.zz.aa

You can also check online at www.intodns.com and input your domain... it will error on the results checking for a reverse zone lookup.

xx.yy.zz.aa = The IP address you're trying to resolve


Update:

When using dig, nslookup, or host it is frequently useful to use a DNS server outside of your control like Google (8.8.8.8) so you get confirmation things are right from a 3rd party. – Zoredache

Zoredache makes a good point, here are the commands for testing/resolving to external/outside DNS servers:

Dig (testing reverse dns on Google's DNS server of 8.8.8.8):

dig -x zz.yy.xx.aa @8.8.8.8

Host and Nslookup (testing reverse dns on Google's DNS server of 8.8.8.8)

nslookup zz.yy.xx.aa 8.8.8.8
host zz.yy.xx.aa 8.8.8.8
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When using dig, nslookup, or host it is frequently useful to use a DNS server outside of your control like Google (8.8.8.8) so you get confirmation things are right from a 3rd party. –  Zoredache Jun 5 '10 at 1:49
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It is the same as doing any kind of DNS lookup.

From a windows command prompt: nslookup.exe <ip address>

From a linux command line: host <ip address>

Note: It is probably best to run these commands from a computer outside of your network, so that you are accessing a public DNS server. Alternatively, both nslookup and host offer ways to specify the DNS server to use.

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