purpose of PTR record ?

Andrew andrew at arda.homeunix.net
Tue Dec 2 04:19:40 UTC 2003


PTR records map IP addresses to names, thus doing the reverse of A records.

One use of PTR records that is being used more and more nowadays is to 
verify the identity of mail servers before mail is accepted from them. I 
know of more than one ISP that will not accept inbound mail from any 
host that does not have a PTR record.

The degree of extra security this provides is debatable, but people are 
doing it nonetheless.

Andrew


mark wrote:

> forward records, like name A maps to IP address w.x.y.z pretty much
> solves the name resolution issue.
> 
> what is the extra or special stuff that reverse PTR records are trying
> to achieve.
> 
> is this true that one of the reasons for this may be:
> "for Chat and FTP servers it is useful to restrict access to hosts in
> certain zones"
> how is this restriction implemented ? (if the above is true)
> 
> 




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