Dns issues in azure VM /devtest labs

Question

Dns issues in azure VM /devtest labs

Gustaf Johansson 0

we have started seeing dns resolution issues in our devtest labs VMs, some urls which are perfectly reachable via the host-computer, just times out in the VM. Have tried setting google custom DNS, but no difference.

Gustaf Johansson 0 Reputation points

2025-03-28T14:44:54.79+00:00

VMs reside in west and north europe.
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-03-31T14:33:57.7466667+00:00

Hello Gustaf Johansson

Please confirm that the Virtual Network (VNet) is properly configured and there are no UDRs blocking DNS traffic. Ensure the DNS server you configured (e.g., Google Public DNS: 8.8.8.8, 8.8.4.4) is reachable from the VM.

You can test this using: nslookup 8.8.8.8. If custom DNS settings are applied at the VNet level, make sure they are correctly configured and propagated to the VMs in the subnet.

If you're using Azure-provided DNS, ensure that no conflicting custom DNS configurations are overriding it. Clear the DNS resolver cache on the VM to ensure there are no stale or corrupted entries by using ipconfig /flushdns.

If Google DNS (8.8.8.8) doesn't work, try other DNS servers. Restarting the VM's DNS Client machine can also help propagate the DNS settings.

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?

Should there be any follow-up questions or concerns, please let us know and we shall try to address them.
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-04-01T09:09:40.3133333+00:00

Hello Gustaf Johansson

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-04-02T09:54:21.4366667+00:00

Hello Gustaf Johansson

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-04-03T10:19:38.0866667+00:00

Hello Gustaf Johansson

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?

1 answer

Your answer

Gustaf Johansson 0 Reputation points

2025-03-28T14:44:54.79+00:00

VMs reside in west and north europe.
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-03-31T14:33:57.7466667+00:00

Hello Gustaf Johansson

Please confirm that the Virtual Network (VNet) is properly configured and there are no UDRs blocking DNS traffic. Ensure the DNS server you configured (e.g., Google Public DNS: 8.8.8.8, 8.8.4.4) is reachable from the VM.

You can test this using: nslookup 8.8.8.8. If custom DNS settings are applied at the VNet level, make sure they are correctly configured and propagated to the VMs in the subnet.

If you're using Azure-provided DNS, ensure that no conflicting custom DNS configurations are overriding it. Clear the DNS resolver cache on the VM to ensure there are no stale or corrupted entries by using ipconfig /flushdns.

If Google DNS (8.8.8.8) doesn't work, try other DNS servers. Restarting the VM's DNS Client machine can also help propagate the DNS settings.

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?

Should there be any follow-up questions or concerns, please let us know and we shall try to address them.
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-04-01T09:09:40.3133333+00:00

Hello Gustaf Johansson

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-04-02T09:54:21.4366667+00:00

Hello Gustaf Johansson

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?
Ganesh Patapati 5,520 Reputation points Microsoft External Staff

2025-04-03T10:19:38.0866667+00:00

Hello Gustaf Johansson

If above is unclear and/or you are unsure about something add a comment below.

Can you please update us if the action plan provided by was helpful?

Answer 1

Rex de Koning 0 MVP

Hi Gustaf,

It's not completly clear from your question if the VM's have internet access for example.

If your VM has no internet access at all and you have a DNS server that is also external it cannot resolve any addresses.

Can you do a ping 8.8.8.8 for example from the VM. This sends a pind request to the Google DNS servers which should give a reply back. If that works you know you have interet access on that VM, of that failes the problem lies on a different level as DNS.

All the best!

Rex

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Dns issues in azure VM /devtest labs

1 answer

Your answer