[2 days left] What’s wrong with your cloud strategy? Learn why multicloud solutions matter with Nimble Storage.Register Now

x
?
Solved

Reverse DNS problem with exchange server

Posted on 2009-05-06
5
Medium Priority
?
352 Views
Last Modified: 2012-05-06
I'm getting this error on emails sent externally occassionally

There was a SMTP communication problem with the recipient's email server.  Please contact your system administrator.
            <mail.(mydomain).org #5.5.0 smtp;550 Reverse DNS lookup failed for host 206.184.xxx.98.>

When I look up the reverse DNS info on 206.184.xxx.98 on www.dnsstuff.com, I get the answer:
Answer:
206.184.xxx.98 PTR record: mail.(mydomain).org. [TTL 43200s] [A=206.184.xxx.103] *ERROR* A record for mail.(mydomain)l.org. does not point back to original IP (A record may be cached).

I changed the A record for mail.(mydomain).com to 206.184.xxx.98 so that it would point back to original IP as the message suggests, but then no mail came in, so I had to change it back.

If it helps, I believe our Netscreen firewall has a public IP of 206.184.xxx.98 and then four VIPs which are 206.184.xxx.99, 100, 101, 103

0
Comment
Question by:tomcurrier
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 2
  • 2
5 Comments
 
LVL 15

Expert Comment

by:tenaj-207
ID: 24318477
The problem is your reverse DNS is set to a different IP address then what your email is coming in on.  So call up your ISP and have them remove the RDNS for 206.184.xxx.98 and move it to 206.184.xxx.103 for mail.(yourdomain).org.
0
 
LVL 65

Expert Comment

by:Mestha
ID: 24319976
I would actually disagree.
It seems like your NAT is setup incorrectly. The traffic is coming in on one IP address and leaving on the other.
If you have your MX records point to one IP address then you need to ensure that there is a reverse DNS record on that address and the NAT is set correctly so the traffic comes out on that address.

Simon.
0
 
LVL 15

Expert Comment

by:tenaj-207
ID: 24320901
Simon's right, as usual.

You need to change your MX record back to .98.  Then change your NAT router/firewall to pass email traffic (port 25) on to the server.

That should correct your NAT issue.
0
 

Author Comment

by:tomcurrier
ID: 24321236
Thank you Simon and Tenaj.  This is where I run up against my newby-ness however.

'You need to change your MX record back to .98"  I'm not sure how to do this.  When I go to Network Solutions and then go to 'edit MX record', I can change the name of the mail server only.  There is no place to input an IP number.  Do you mean I should change the A record of mail.(mydomain).org back to 98 from 103?

Secondly, I don't know how to change my NAT.  We have a netscreen 25 and one of the Ethernet ports is IP 98.  Within this Ethernet 3, I have 4 virtual IPs, 99, 100, 101,  and 103.  103 is up and has Port 25 pointing to a Server which hosts NoSpamToday, from where our email is forwarded.

Many thanks in advance for your help.  
0
 
LVL 65

Accepted Solution

by:
Mestha earned 2000 total points
ID: 24328111
I wouldn't touch your MX records as that could impact on your email delivery. Leave the MX record setup alone.
Get your ISP to set the reverse DNS record on that IP address. Then you just need to get the NAT corrected. I cannot help with Netscreen - I haven't seen one for over 18 months.
Ask a separate question on that in one of the firewall zones.

Ideally what you want is a one to one NAT for the Exchange server. Of course that will presume if you are using OWA etc and on what IP address.

Simon.
0

Featured Post

What does it mean to be "Always On"?

Is your cloud always on? With an Always On cloud you won't have to worry about downtime for maintenance or software application code updates, ensuring that your bottom line isn't affected.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I don't pretend to be an expert at this, but I have found a few things that are useful. I hope that sharing them here will help others, so they will not have to face some rather hard choices. Since I felt this to be a topic of enough importance and…
The main intent of this article is to make you aware of ‘Exchange fail to mount’ error, its effects, causes, and solution.
In this video we show how to create a Contact in Exchange 2013. We show this process by using the Exchange Admin Center. Log into Exchange Admin Center.: First we need to log into the Exchange Admin Center. Navigate to the Recipients >> Contact ta…
The video tutorial explains the basics of the Exchange server Database Availability groups. The components of this video include: 1. Automatic Failover 2. Failover Clustering 3. Active Manager
Suggested Courses

649 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question