DNS Reverse lookup problem

Hatchet02 · 07-09-2008, 01:17 PM

Recently some e-mail servers like (Comcast and AOL) have implemented a requirement for proper reverse lookups and PTR's for your domain before they will accept any incoming mail from your mail server. No problem right! (So I thought). I am the administrator of our DNS server and I setup a proper reverse lookup zone with pointers (PTR's) to the host domain. However, when I do a reverse lookup using (http://howismydns.com) and others like it I get "no reverse lookups available". But if I add the ip address as the host name in the lookup it shows the PTR's. but a pure reverse lookup fails. Any one have a suggestion or is an expert in this area who can work with me to fix this problem?

**djaburg** · 07-09-2008, 09:59 PM

Basically you need to have the MX records for your domain pointed to the external IP address of your site. Then you need to make sure you have exchange server configured correctly to accept incoming messages for your domain. Basically the reverse DNS is NOT something that you can do from your end, on your DNS servers, unless you're a domain registrar. If you have your website hosted with a hosting company, then they have the control over the DNS records for your domain. Typically all you'd need to do is have them change the MX record to point to your server.

If your situation is different, please explain.

Hatchet02 · 07-10-2008, 06:07 AM

I am a domain registrar. I host our site on our T1. with our own public DNS servers. The DNS servers pass all tests including the MX record, but the reverse lookup is the only thing failing. Do you suppose AT&T (whom I have the T1 line from) is handling the reverse lookup for my subnet? Maybe that is why it is not making it back to my servers.

**djaburg** · 07-11-2008, 12:40 PM

All the reverse DNS really does is queries DNS to find WHERE mail from yourdomain.com should be coming from and then it compares that to the IP in the header and if they don't match, it blocks the message assuming it's being sent by someone that's NOT on the actual server for the domain.

Hatchet02 · 07-13-2008, 08:19 AM

The problem is solved, Thanks for the input. It did turn out that AT&T had thier DNS server doing the reverse lookup for the subdomain. Even though I am not hosting with them, I was suppose to have just a straight un-managed T1 line. I have our own public server with our domain registered to it. Once I spoke to them they corrected the problem. Thanks again

Hatchet

07-09-2008, 01:17 PM	#1 (permalink)
Hatchet02 Registered User Join Date: Jul 2008 Posts: 3 OS: Windows 2000 server	DNS Reverse lookup problem Recently some e-mail servers like (Comcast and AOL) have implemented a requirement for proper reverse lookups and PTR's for your domain before they will accept any incoming mail from your mail server. No problem right! (So I thought). I am the administrator of our DNS server and I setup a proper reverse lookup zone with pointers (PTR's) to the host domain. However, when I do a reverse lookup using (http://howismydns.com) and others like it I get "no reverse lookups available". But if I add the ip address as the host name in the lookup it shows the PTR's. but a pure reverse lookup fails. Any one have a suggestion or is an expert in this area who can work with me to fix this problem?

07-09-2008, 09:59 PM	#2 (permalink)
djaburg TSF Enthusiast Join Date: May 2008 Posts: 1,321 OS: XP SP3/Vista/7 Server 2K/2K3/2K8	Re: DNS Reverse lookup problem Basically you need to have the MX records for your domain pointed to the external IP address of your site. Then you need to make sure you have exchange server configured correctly to accept incoming messages for your domain. Basically the reverse DNS is NOT something that you can do from your end, on your DNS servers, unless you're a domain registrar. If you have your website hosted with a hosting company, then they have the control over the DNS records for your domain. Typically all you'd need to do is have them change the MX record to point to your server. If your situation is different, please explain. __________________ Computers make it easier to do a lot of things, but most of the things they make it easier to do don't need to be done. The inherent vice of capitalism is the uneven division of blessings, while the inherent virtue of socialism is the equal division of misery. Last edited by djaburg; 07-09-2008 at 10:01 PM.

07-10-2008, 06:07 AM	#3 (permalink)
Hatchet02 Registered User Join Date: Jul 2008 Posts: 3 OS: Windows 2000 server	Re: DNS Reverse lookup problem I am a domain registrar. I host our site on our T1. with our own public DNS servers. The DNS servers pass all tests including the MX record, but the reverse lookup is the only thing failing. Do you suppose AT&T (whom I have the T1 line from) is handling the reverse lookup for my subnet? Maybe that is why it is not making it back to my servers.

07-11-2008, 12:40 PM	#4 (permalink)
djaburg TSF Enthusiast Join Date: May 2008 Posts: 1,321 OS: XP SP3/Vista/7 Server 2K/2K3/2K8	Re: DNS Reverse lookup problem All the reverse DNS really does is queries DNS to find WHERE mail from yourdomain.com should be coming from and then it compares that to the IP in the header and if they don't match, it blocks the message assuming it's being sent by someone that's NOT on the actual server for the domain. __________________ Computers make it easier to do a lot of things, but most of the things they make it easier to do don't need to be done. The inherent vice of capitalism is the uneven division of blessings, while the inherent virtue of socialism is the equal division of misery.

07-13-2008, 08:19 AM	#5 (permalink)
Hatchet02 Registered User Join Date: Jul 2008 Posts: 3 OS: Windows 2000 server	Re: DNS Reverse lookup problem The problem is solved, Thanks for the input. It did turn out that AT&T had thier DNS server doing the reverse lookup for the subdomain. Even though I am not hosting with them, I was suppose to have just a straight un-managed T1 line. I have our own public server with our domain registered to it. Once I spoke to them they corrected the problem. Thanks again Hatchet