DNS propagation and internal network

By m.watson ·
Hi guys,

I recently changed my IP address to a domain name, I went through the 3 days of propagation, but what I have found is that the mail extension to my domain name cannot be seen on the inside of my own network. It can be pinged and looked up from other computers, but it would appear that my internal DNS does is not aware of the change, so mail clients constantly return an error that the host name cannot be found.

Can anyone point me to a simple but effective solution to this problem?

I am running Windows 2003 Server, and using a 3rd party domain host (


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All Answers

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Did you configure the MX record on your DNS server?

by seanferd In reply to DNS propagation and inter ...

If you changed to domains internally, or the mailserver has a new name, you will need to configure this.

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DNS propagation and internal network

by m.watson In reply to Did you configure the MX ...

I tried something, but my problem is that I never had to set that in the first place...could it just be something that needs to be refreshed?

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You can always flush the reolver caches.

by seanferd In reply to DNS propagation and inter ...

You may need to do this on the server and the clients.

If your MX record has changed with your new situation, you will have to change it. It will not do this by itself.

And for a better understanding, you will have to clearly explain what has changed where: In your local network, at the hosting service, etc.

A hosting service cannot be in control of your LAN traffic, so take that into consideration. If you expect to reach the mailserver by going out over the internet then bouncing back to hit your Public email address, the mailserver will have to be able to allow your users access to their accounts or whatever over the public side (which I would not really advise).

So, why not tell us what happens when a user attempts to use the mailserver - what errors? Have you traced packets with Wireshark or similar to see what is happening?

Or is this supposed to be a mailserver provided by the hosting company? What are they providing for you? Just a domain name? More than that?

You can try looking up your domain name with a service like , and see what the MX records listed show. You can try for a bunch of DNS analysis.

For further posts here, you will need to be a bit more clear as to how users used to connect to the mailserver (route, etc.), and how you expect to connect to the mailserver now (route, resolution, etc.).

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Some wizard did it for you...

by TobiF In reply to DNS propagation and inter ...

Most probably, while you were setting up you mail server, some wizard made the needed internal configuration.

Also remember, from the internet, your mail server will be located on a public ip address which is then port-forwarded to the inside, but from the inside, the same server is found on a private address.

If you've started using a different server name, which is not captured and translated on the inside, then your internal clients will find an external address. And it's not a given that your router/firewall will happily loop back such traffic to the inside.

So, you need to dig into the internal dns server and have a look there.
Also, maybe you need to adjust "default domains" on the inside (hardcoded ip configuration and/or dhcp)

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