How to configure Reverse DNS, PTR and MX records for private email server behind Comcast Static IP
Hello, I have some questions on how to set-up Reverse DNS, PTR and MX records for our private Exchange email server sitting behind a Comcast Static IP address.
We run our own Exchange server on a private network behind static IP address: 22.214.171.124. Our domain is www.estarmail.com and mail.estarmail.com for email. I have registered these domains and set up Reverse DNS, PTR and MX records at REGISTER.COM our registrar.
When I go to DNSQUERY.COM I get no results for A, CNAME, MX and TXT queries. The DNS and PTR query properly return estarmail.com for my IP. The reverse DNS query returns an undefined (???) PTR to my domain. The WHOIS query returns Comcast Business Communications, LLC.
What can I do to get the various missing or incorrect DNS records set up so they will resolve properly to our static IP and domain?
Office: +1 (773) 697-8283
Cell: +1 (847) 372-2381
6 years ago
A domain registry like register.com is only authoratative for forward records like A records and MX records. You can only setup PTR records with the hoster of the IP address block - in this case Comcast.
The by the book process is contact Comcast on the phone Mon-Fri 8-5pm Eastern time.
Incidentally your PTR isn't correct. Take a look at the following:
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation. All rights reserved.
Default Server: UnKnown
> set type=mx
estarmail.com MX preference = 0, mail exchanger = mail.estarmail.com
estarmail.com nameserver = dns142.a.register.com
estarmail.com nameserver = dns167.b.register.com
estarmail.com nameserver = dns223.c.register.com
estarmail.com nameserver = dns249.d.register.com
mail.estarmail.com internet address = 126.96.36.199
dns142.a.register.com internet address = 188.8.131.52
dns167.b.register.com internet address = 184.108.40.206
dns223.c.register.com internet address = 220.127.116.11
dns249.d.register.com internet address = 18.104.22.168
> set type=a
> set type=ptr
22.214.171.124.in-addr.arpa name = estarmail.com
(should be mail.estarmail.com)
91.70.in-addr.arpa nameserver = dns104.comcast.net
91.70.in-addr.arpa nameserver = dns102.comcast.net
91.70.in-addr.arpa nameserver = dns103.comcast.net
91.70.in-addr.arpa nameserver = dns105.comcast.net
91.70.in-addr.arpa nameserver = dns101.comcast.net
dns101.comcast.net internet address = 126.96.36.199
dns101.comcast.net AAAA IPv6 address = 2001:558:fe23:8:69:252:250:103
dns102.comcast.net internet address = 188.8.131.52
dns102.comcast.net AAAA IPv6 address = 2001:558:1004:7:68:87:85:132
dns103.comcast.net internet address = 184.108.40.206
dns103.comcast.net AAAA IPv6 address = 2001:558:1014:c:68:87:76:228
dns104.comcast.net internet address = 220.127.116.11
dns104.comcast.net AAAA IPv6 address = 2001:558:100a:5:68:87:68:244
dns105.comcast.net internet address = 18.104.22.168
dns105.comcast.net AAAA IPv6 address = 2001:558:100e:5:68:87:72:244
Forward and reverse records only exist for hostnames not domains.
A domain (estarmail.com) can have a MX record and it can have an A record but the MX
record is only used for routing mail. The A record is not. CNAME records are not used
for routing mail at all. Setting a PTR (reverse DNS) record to point to a domain instead of
a hostname is nonsensical.
New problem solver
6 years ago
Thank you, I have updated the PTR record at REGISTER.COM and opened a ticket at Comcast.