Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

This should be a simple one:

We have an inhouse mail server, so our outlook users hit it locally.. mailserver.mydomain.local

But smartphone and laptop users need to be able to hit it from inside and outside. I assume that a simple solution is to set up laptops and smartphones to hit the external address and then set a record on my internal DNS server to resolve to its local IP address.

Is this an effective solution, and can you tell me how I would set it up in (windows server 2008 R2) DNS?

share|improve this question
up vote 0 down vote accepted

We use the exact set up in multiple sites.

External - Log into your domain control panel and set up your domain DNS with an A Record for mail ( that points to your server's static IP. eg

Internal - Open DNS managment. Expand Server>Foward Lookup Zones. Add a forward lookup for that has an A Record for the mail server's static IP. eg

We have never had any complaints from anyone about any server access glitches due to them leaving the office etc. Works on laptops and smartphones. Just ensure that the DNS server on the wireless routers/hubs/switches is the Windows Server 2008 box, otherwise nothing will resolve.

share|improve this answer

That solution has one drawback: DNS answers are cached, usually for several hours. This causes a situation where users will not really be able to navigate back and forth between internal and external domains.

The typical solution is to setup a relay server that can be reached both internally and externally with the same IP address.

share|improve this answer
Windows clients typically dump their DNS cache when a network PHY goes down. So the DNS cache problem shouldn't occur as the PHY needs to go down and back up again when they move from internal to external or vis versa. – Dom Nov 3 '11 at 13:52
Yes, but I don't think that this applies to smartphones – Stephane Nov 3 '11 at 14:00

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.