Sunday, October 19, 2014

Unable to resolve microsoft.com address from Azure VM

Recently I created a few virtual machines in Microsoft Azure, promoted a domain controller and tried to connect to http://www.microsoft.com to download a few patches. Nothing special you would think. Unfortunately something manifested that I did not expect. I was unable to access any Microsoft related page and would find the following error message “This page can’t be displayed. Other websites such as http://www.google.com worked fine.


This page can't be displayed


ping Microsoft.com

I raised a call with Microsoft support for this case and at the same time started to investigate the issue myself. The first thing that came into mind was checking the DNS Forwarders. And funny enough I immediately noticed that my DNS server in Azure had a Forwarder configured that cannot be resolved. The address 168.63.129.16 is the one to keep an eye out for.

Forwarder - Unable to resolve DNS servers

Resolution

To resolve this issue simply update the DNS forwarder on the DNS server to one that does work, for example 8.8.8.8, which is the Google public DNS server. It’s recommended to delete the entry that cannot be resolved. And as a safety measurement I recommend adding in a secondary DNS servers to provide a failover when the primary is unavailable.


Updated Forwarder with 8.8.8.8 and 8.8.4.4

This change will apply immediately and you’ll find that http://www.microsoft.com, and other Microsoft pages, are resolved without any issues.


Microsoft.com is now resolved

 I’ve only just started blogging about my adventures in Azure so please feel free to comment.

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