Purpose of reverse zone

[Len Conrad]

>What is the purpose of having a reverse zone?

to map ip addresses to hostnames (PTR records), the opposite of forward 
zone which maps hostnames to ip addresses.

>   I have heard of some
>mail servers rejecting mail because no reverse zone is available for
>the email domain mail was sent from.

some do, but such a restriction produces too many false positives as many 
non-abusive mail servers don't have their reverse set up.

Len


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