troubleshooting Question

Can Cisco resolve internet address internally

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jgrammer42 asked on
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Here is the situation.  I have an internet domain of CORPORATION.COM

Exchange is the mail server with the DNS name of MAIL.CORPORATION.COM on the internet.

MAIL.CORPORATION.COM is used by laptop, (for example), for Outlook Anywhere access.

MAIL.CORPORATION.COM resolves to internet address of  (again, just an example)

My Cisco ASA NAT's the external IP of to the internal LAN address of

All of that works great.  No problems.

However, when someone with a laptop comes into the corporate office, and tries to resolve the name of MAIL.CORPORATION.COM,  the internet DNS responds with which the Cisco is unable to resolve or map back to the internal network of, which is the Cisco's internal known IP network.

For years, the way around this is to set up on the INTERNAL LAN DNS a CORPORATION.COM domain, that all local LAN clients would use to resolve back to the internal LAN network of 192.168.1.y, instead of to an external Internet address.

Frankly, I HATE that solution.  I always thought it was kludgy at best.

So, the question is this, is there a way to configure the Cisco that if it sees an internet address that maps to its known internal LAN network IP, it will automatically respond back with that internal LAN address instead of just getting stuck in a loop?

Thank you in advance,
Craig Beck
Network Architect and EE TA
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