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Exchange Server Public IP Reverse DNS

We have an Exchange server with an assigned public IP. Our website/email is hosted by our ISP. When email is sent from our Exchange server, reverse DNS fails and we can't send email to certain clients.

I am going to set up a PTR record with our ISP to forward the email automatically to our Exchange server so I can implement reverse DNS to the exchange server's public IP address.

if our company's website/email domain name is mycompany.com and the exchange server public ip is 10.9.8.7 then should the reverse DNS point to mycompany.com, mail.company.com or what?

Lastly, is this the only solution to reconciling Reverse DNS to our Exchange Server?

thanks,

RantCan

I think your question is broader than DNS and PTR records.

I need some clarification: when you say "email is hosted" do you mean MX records or a mail server that is literally forwarding mail?

If your exchange is Internet available on Port 25, then you should ensure it is significantly hardened. From a security perspective, using exchange in this manner is supported but massively insecure. I have used a variety of providers that use the mxlogic portal (McAfee, Spamsoap) and this helps keep your exchange from getting essentially DDOS'd on 25, as exchange will only take SMTP traffic from one IP address.

frdbadf

ASKER

I have a similar setups with other locations, some have the mail forwarded to AppRiver who scrubs for spam and the forwards to the Exchange server public IP, and in all cases we have firewalls that forward port 25 on the public IP to the Exchange server on the internal LAN.

when I use http://ipadmin.junkemailfilter.com/rdns.php to check RDNS on the Public IP it responds with

RDNS for xx.xxx.xx.xx is: [mail.ourdomain.com] - (PTR record - xx.xx.xxx.xx.in-addr.arpa)

ERROR - Lookup Failed for [mail.ourdomain.com]

ERROR - Reverse Lookup Failed
IP [xx.xxx.xx.xx] does not match []

I perform NSLookup of mail.ourdomain.com and it says Server: unknown

I'm missing a record? MX?

thanks,

cpmcomputers

You need to request your ISP to set rdns on their system for the external ip to "mail.yourdomain.com" not those of your own Dns management
This is why it is returning an in arpa address

frdbadf

ASKER

I worked over the phone with the ISP yesterday setting up rdns but it still does not resolve correctly.

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cpmcomputers

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frdbadf

ASKER

We are using CBeyond, bought recently by Birch communications. I will pass this on and get back to you.

thanks,

cpmcomputers

Hi

Just to illustrate the point you might want to see this link

http://btbusiness.custhelp.com/app/answers/detail/a_id/8763/~/how-can-i-set-up-a-reverse-dns-on-my-domain-name%3F

Hope you get it sorted soon