How do you find out what the PTR record is to your IP address?
In any Unix/Linux bash terminal type:
dig -x 64.226.42.29
Obviously instead of the number after dig -x you put your own IP. Remember PTR records are for IP addresses not domain names.
For more info check here and here.
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You can also find PTR record for ip here http://www.magic-net.nl/dns-and-ip-tools.php