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Unable to resolve external hostname internally

joseph.iacona
Level 1
Level 1

Hello,

I am working on adding a mapping to our external address for our mail server - let's call it mail.example.com

I would like to be able to access mail.example.com internally for our user's smartphones - if they access our company WiFi they are not able to get mail using the mail.example.com as the server name in their phone setups.  However, once they leave the office and use any other WiFi it works fine. Also, I am unable to ping that address from any internal device.  I believe also this is the reason Exchange accounts do not work on our site to site VPN connections.

I have a ASA 5520 and work primarily in the ASDM 6.4 to do configurations in the main office and have 5510 in our site to site connections.

Any help would be greatly appreciated!

6 Replies 6

mvsheik123
Level 7
Level 7

Hi Joseph,

I guess mail.example.com resolves to external IP. So the company WiFi goes thru the same ASA as your mail host connected to? If so, you may need DNS doctoring. Based on ASA version check for DNS doctoring docs.

hth

MS

It does - mail.example.com resolves to our public IP for the office ASA -- thanks for the response.

However, can someone elaborate more?

Hello Joseph,

Are you using an internal or external DNS?

also what code are you running?

Regards,

Julio

Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC

Hello Julio,

Not sure on the code. Using external DNS for outside queries.

Thanks,

Joseph

Hello Joseph,

Please do a show version ( you will get the OS version of your ASA). Then based on that I will provide you the resolution to this,

Regards,

Julio

Julio Carvajal
Senior Network Security and Core Specialist
CCIE #42930, 2xCCNP, JNCIP-SEC

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