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External DNS MX configurations settings conflict between MX, Exchange, external host provider, and Citrit server

Posted on 2013-05-12
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Last Modified: 2013-06-02
We recently had a company contact us abuot not being able to send us email. They went through the process of using MX Toolset.

Upon which they found that kxxchemicals.com resolved to external ip address 70.42.x.161 (which is correct and configured on our sonicwall for smpt) but they also discovered another IP Address 70.42.x.163 was also resoving to kxxchemicals.com using data1.kxxchemicals.com; this is our Citrix server. All this makes since (pretty much). The problem here is that i dont not know how to correct it due to my current level of DNS internal/external routing and such.

This is the reason I got from our Network guy:

Data1 is an alias for 70.42.x.161. The purpose is to be able to host multiple sites with the same WAN IP (MX, Citrix etc…).  This setup was there from the beginning. We need to review all DNS records and tell them what change you want them to make. You should tell them either point to IP address or alias. They will not know what you are talking about. All they know is making change to dns records.

I am able to cut/paste internal / external DNS, sonicwall settings, available ext ip addresses. I just need help on figuring out which open is best for our current situation and why?

I would also like to know where/how our Citrix server is showing up with a MX record, especially since it is not located on our current external DNS host company. Could it be that this is a left over entry from another host?
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Question by:Group_007
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6 Comments
 
LVL 26

Expert Comment

by:Tony Johncock
ID: 39159474
Well I would start by confirming yourself that these external names have MX records:

You can either use nslookup.exe with set type=mx followed by the names

I actually tend to use an external DNS Server too if possible:

so, from a command prompt:

Nslookup
server 8.8.8.8
set type=mx
servername1
servername2

I would also head over to www.mxtoolbox.com and use their tools to get more information.

As long as the MX record resolves to the correct A record for the correct IP address, and the firewall allows port 25 through to whatever is receiving email, it shouldn't matter if you share that same IP on another name for Citrix.
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Author Comment

by:Group_007
ID: 39160247
I have confirmed for myself through MX Toolset prior to posting this question. Everything that resolves to the kxx.com with IP address xxx.xxx.xxx.163 and data1.kmxxxx.com is correct.

My question was where can I find the reason that Citrix is using xxx.xxx.xxx.161 is using MX record to resolve to the data1kmxxxx.com . And yes this configuration is causing issues external users sending email to our domain. Citrix should not be using MX record and yes all the other stuff is correct (port 25 / smtp).
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LVL 26

Accepted Solution

by:
Tony Johncock earned 500 total points
ID: 39160426
Citrix never uses an MX record - someone must have added it in to your external DNS somewhere.

Indeed, Citrix never sets any external DNS records automatically - they are always added manually.

A good start is usually to confirm the name servers - set type=NS in the lines above - as they are usually handled by your ISP.

Otherwise, either check their control panel or give them a call.
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Author Comment

by:Group_007
ID: 39160986
will check it out and reply shortly...
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LVL 1

Author Closing Comment

by:Group_007
ID: 39214263
Yes the problem was in the external DNS records. Someone had added/rearranged DNS entries without cleaning up old entries.

Thank you!
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LVL 26

Expert Comment

by:Tony Johncock
ID: 39214553
Thanks for the points, but may I ask why only the 'B' grade?
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