reverse DNS

Posted on 2004-10-27
Medium Priority
Last Modified: 2013-12-06
i can no longer send mail to AOL they told me that i do not have reverse dns setup
and will not be able to sent mail to them untill i set it up
here is where im confused
when mail goes out of my network aol is picking up my firewalls ip adress  not my mail server
so do i set up a pointer and a A record to my firewall for reverse dns since this is what they seeing on their end
i allready have an a record and an mx record setup for my mail server
ex.. A record......mail1.helpme.com
    MX record......mail1.helpme.com
do i setup this?
    A record......mail1.helpme.com (FIREWALL)
   POINTER  .....mail1.helpme.com (FIREWALL
can you have 2 A records with the same name that point to different ip addresses as the example above
Question by:dano992
LVL 97

Accepted Solution

Lee W, MVP earned 500 total points
ID: 12430091
You can have two A records with the same name, but you should know in reverse lookups, only the first entry will ever be provided.

Assisted Solution

alexai earned 500 total points
ID: 12430819
Adding more A records, pointing to your firewall will only confuse all mail servers, for I'm sure your firewall does not handle mail.

You need to create (if you haven't yet) a reverse lookup zone, in your DNS server:


and populate it with the rest of the IP address as subdomains (50 and 200) and then add there your MX's FQDN.

or a single zone:

it's up to you and how many public IP addresses you have

Windows doest it automatically for you. If you're on *NIX you have to edit the files by hand, unless there is a GUI, like SAM in HP-UX.
LVL 11

Assisted Solution

PennGwyn earned 500 total points
ID: 12435346

Note that this zone entry will only ever be FOUND if the ISP responsible for 200.50.100.* both

(a) Implements a 100.50.200.in-addr.arpa zone, and

(b) Delegates the zone to your DNS server.

For a single host, (b) represents more work than most ISPs want to do, and it's simpler for THEM to resolve the "hostname" 10 within their Reverse DNS zone for you.  Neither approach is something you can achieve without them.

(<RANT ON>AOL's *bogus* assumption is that ISPs always provide reverse DNS for their static customers, and never for their DHCP customers (who shouldn't be running mail servers on those links).  Not only are a lot of people in your situation, there are plenty of cable/DSL ISPs who provide useless Reverse DNS entries for their entire address space, just so idiots like AOL can't screw things up for their customers even if they are running compromised spambots. </RANT OFF>)

LVL 25

Assisted Solution

mikeleebrla earned 500 total points
ID: 12435869
FYI you also have SPF records in order to send mail to aol now: see below:


THis page will actually walk to through and set up the spf record for you:


Hope this helps


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