VM - DNS unable to resolve

Question

I am new to Azure, please bear with me. I created a Windows 2012 VM server. When I try to connect the server using RDP from the Azure portal, it is working fine. However, when I tried to access with the DNS name, which I setup in the portal, it is not resolving. Then I setup DNS forward look up in VM, which still did not help. I am not sure if this process is even needed. When I do 'Test Connection' in the portal, I get "Network connectivity blocked by security group rule: DefaultRule_DenyAllInBound". So I allowed DNS(TCP) in Inbound port rules. It still did not help. I do not understand why I cannot even ping the public IP. To sum up, 1. How do I resolve the DNS name? Is setting up DNS forward/reverse look up in the VM needed? 2. Why can't I ping public IP of the VM? I appreciate your time reading this post.

Answer 1

Hi @Kei Moon ,

Related to question 1:
You are talking about the DNS name resolution for the public IP of the VM?
The name resolution for the public IP of the VM is done by MS DNS servers. No need to change anything in the VM OS config.

Related to question 2:
If you have Network Security Groups (NSGs) associated in the subnet or to the VM: ICMP Protocol is blocked by default
If it's a Windows VM: Maybe the OS Firewall is blocking ICMP?

This is the configuration of a VM (Windows, OS Firewall allowing ICMP) with public IP, DNS name for public IP and allowing inbound ICMP rules in the NSGs:

The result:

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(If the reply was helpful please don't forget to upvote and/or accept as answer, thank you)

Regards
Andreas Baumgarten

Answer 2

Thank you for you help. I do not have ICMP as a default rule.