Setting up reverse DNS correctly

[Justin Randall]

There are two solutions in this case, the one that is least likely to be the 
actual solution would be to ask your ISP to delegate a portion of the 
reverse records (PTR RRs) over to your name servers.  There is a CNAME hack 
that can easily accomplish this.

The most common and more likely solution is to contact you ISP and request a 
reverse entry be made in their records to the effect that a query against 
your IP will resolve your mail server FQDN.

For example,

$ORIGIN 0.0.10.in-addr.arpa.

4    1H    IN PTR        your.mail.server.

Given this entry, an nslookup on the IP 10.0.0.4 will result in the hostname 
your.mail.server.

I hope this helps.

Justin

>From: cching at mqsoftware.com (Craig L. Ching)
>To: comp-protocols-dns-bind at isc.org
>Subject: Setting up reverse DNS correctly
>Date: 14 Jul 2004 11:34:51 -0700
>
>I recently had a sent e-mail to comcast.net bounced back to me saying
>something about "only valid hosts may send."  Tracking it down, I
>found (using www.dnsreport.com) that I might not have reverse DNS set
>up correctly for my domain name.  Could somebody help me out with
>this?  Here is the db file for the domain (unaltered).  The named
>daemon is bind 9 (not sure of the exact version).
>
>$TTL 86400
>webasap.net. IN SOA sumo.webasap.net. cching.sumo.webasap.net. (
>			2004071401	; Serial
>			10800		; Refresh after 3 hours
>			3600		; Retry after 1 hour
>			604800		; Expire after 1 week
>			86400 )		; Minimum TTL of 1 day
>webasap.net. IN NS sumo.webasap.net.
>
>;
>; Host addresses
>;
>sumo.webasap.net.	IN A	67.107.38.61
>www.webasap.net.	IN A	67.107.38.61
>
>;
>; MX records
>;
>webasap.net.			MX 0		sumo.webasap.net.
>
>;
>; Aliases
>;
>sumo.				IN CNAME	sumo.webasap.net.
>
>I have tried a few things in the last couple of days, but haven't
>gotten dns report to tell me it's set up right, so I've set it back
>the way it was originally.  Thanks for any help and let me know if I
>need to post any other information!
>
>Cheers,
>Craig
>

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