Custom Internal IP for DDNS address

A client is using example.dyndns.org to point to their public WAN interface which is used for external Exchange access to their Windows 2003 server. However, devices from within their internal network can't use that address to connect to Exchange from within the internal network. What we need to do is setup DNS on the Windows server to point to the internal IP of the server for example.dyndns.org. That way a user can use Exchange on their mobile device without ever changing a setting. I've tried doing that a few ways but it's not working.

For example:

Public: example.dyndns.org -> 24.22.22.21
Internal: example.dyndns.org -> 192.168.1.10

Thanks!
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sc456aAsked:
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Adam BrownSr Solutions ArchitectCommented:
There are a couple ways you can accomplish this, but there are issues with either method.

1. Create a new DNS Forward Lookup Zone in DNS on one of your Domain Controllers, this zone should be for dyndns.org. Once you have the zone, you can then create an A record for example.dyndns.org that points to the internal IP address. Note, though, that any other dyndns.org addresses your users need to use will also have to have IP addresses added in this zone in order to work. This may create a bit more work for you to manage that zone.

2. Create a script that will modify the hosts file and add an entry in it for example.dyndns.org that points to the internal IP address. Configure it as a login script, or use a utility like PSExec to run the script on all the workstations. This technique will result in less ongoing work, but will fail if the computers are not on or have firewalls that block the PSExec access method (if you configure it as a logon script, it will work, but will run every time someone logs on, and permissions may be an issue).
footechCommented:
For the issues mentioned by acbrown2010 in option 1, if you only need to create a record for example.dyndns.org and yet leave resolution of other *.dyndns.org records to their public records, then create a zone for example.dyndns.org and then inside it create an A record and leave the name blank and point it at your internal IP.  Once created it will show the name as "same as parent folder".

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sc456aAuthor Commented:
Thanks to you both!
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