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Olivier Dauby
Asked: 2015-10-20 05:30:42 +0800 CST

Azure internal DNS search suffixes

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I mainly use Azure for IaaS purposes (Linux and Windows VM's). We have a strict Front-End (FE) / Back-end (BE) segregation policy.

FE and BE are in the same Virtual Network, but in different Subnets/Cloud Services.

I've noticed that FE and BE VM's are getting different DNS suffixes via DHCP:

  • FE machines get frontend-something.a9.internal.cloudapp.net as DNS search suffix
  • BE machines get backend-something.a1.internal.cloudapp.net as DNS search suffix

FE machines can reach each other simply by hostname thanks to this search suffix but can't reach BE machines unless I add the BE DNS search suffix in their config.

My question is: Is there a way (via PowerShell / Azure CLI) to find out what DNS suffix is used in a subnet/Cloud Service ?

I need this to automate deployments and I can't predict what the internal DNS search suffix will be (like the "a9" and "a1" that I don't control and that appear in the DNS search suffixed examples above).

Kind Regards,

O.

powershell

1 Answers

  1. Best Answer

    If you use Get-AzureVM with -Debug you can look in the XML for InternalDnsSuffix. However, if you use ARM-based deployments, all VMs in the VNET get the same suffix.

    Regards Gareth

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