[CALUG] help with dns reverse PTR record problem

[Daniel Deighton]

Duane,

Requiring the PTR record to match the A record is an often-used
technique to reduce SPAM. You will likely run into it again, so it is
best to correct the problem as soon as possible.

With godaddy, you are controlling the records for your domain (i.e.
example.com). As you know, you can set any record you like for
example.com. These are the forward lookups to translate from name to IP
address.

The problem is that you need to enter records for the reverse lookups or
in-addr.arpa domain. These records resolve IP addresses back to names.
You don't control these records. Since you aren't using godaddy hosts,
they don't control these records either -- as you found out, they won't
be able to help you. You will need to contact your ISP for help in
setting the PTR record.

As a real-world example, you can take one of our MX records,
mx1.aplura.com. mx1.aplura.com resolves to 205.134.167.68. We set that
up in our DNS servers, which takes care of the forward lookup. The block
of IP addresses that includes 205.134.167.68 is "owned" by AINet, our
ISP in this case. We had to submit a request to AINet to add the PTR
record into their DNS table. Once completed, the PTR record matched the
A record.

Hopefully this makes sense. Let us know if you need more information.

 -Dan

-- 

Daniel Deighton
Partner - Aplura, LLC
ddeighton at aplura.com
410.241.4845


On Sun, 2010-11-28 at 21:08 -0500, Duane Tucker wrote:
> Hi all,
> 
> I'm looking for someone who would be willing to help me with a DNS 
> problem. I'm willing to pay for your time.
> 
> Background: I administer the network and servers for a small company. I 
> have a linux server running postfix for outgoing smtp email. The domain 
> is registered with godaddy and I use the godaddy DNS Manager tool for 
> dns control.
> 
> The problem is this: when someone inside the network attempts to email 
> anyone at a comcast.net address,  Comcast rejects the emails with the 
> following message:
> 
> Nov 28 20:18:17 mailserver postfix/smtp[10207]: 4F0E36FD08: 
> to=<teset at comcast.net>, relay=mx1b.comcast.net[76.96.62.116]:25, 
> delay=19637, delays=19636/0.08/1/0, dsn=4.0.0, status=deferred (host 
> mx1b.comcast.net[76.96.62.116] refused to talk to me: 554 
> imta04.westchester.pa.mail.comcast.net comcast 69.85.36.83 Comcast 
> requires that all mail servers must have a PTR record with a valid 
> Reverse DNS entry. Currently your mail server does not fill that 
> requirement. For more information, refer to: 
> http://help.comcast.net/content/faq/PTR)
> 
> 
> Comcast is the ONLY domain in almost 2 years that we have this problem 
> with. Luckily, we almost never need to email anyone with a Comcast 
> address. This problem has reared its ugly head only 3 or 4 times. It 
> drives me nuts, however, that I can't figure out how to fix the problem. 
> This weekend I even stumbled through setting up my own DNS server, using 
> bind, but then couldn't figure out how to implement it. The reason for 
> my confusion here is that in the godaddy dns manager, it requires me to 
> enter a FQDN for the name servers, not an IP address. Well, if the 
> purpose of the DNS server is to resolve names, and the DNS server is 
> running within the same domain that your trying to resolve, how in the 
> world would it ever get there for resolution?!?
> 
> Now you would think that the answer would be easy. Since I'm managing 
> dns entries with the godaddy dns manager, why not just put a reverse PTR 
> record there? But no, that's just too easy. Godaddy doesn't allow you to 
> enter PTR records. They do have some perverted way to enter TXT records 
> with a PTR embedded, but I can't figure that out either. When I called 
> godaddy tech support, they politely informed me that since I don't use 
> their hosts, they can't provide support for the dns entries. Sigh. By 
> the way, here is a link to a godaddy support page discussing the 
> TXT/PTR/SPF "thing".
> 
> http://community.godaddy.com/help/article/680
> 
> So if anyone reading this thinks they can help, please do let me know. 
> I'm tired of spending weekends now and then chasing my tail. I know just 
> enough about all this to be dangerous. The answer could be just one 
> small step away and I simply can't see it.
> 
> Many thanks,
> Duane Tucker
> 
> 
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