How Do I Address Other VMs in the VNET By FQDN?

Question

I have 2 VMs on the VNET in Azure.

The ports are open in the NSG.

I can access the ports when I use the IP address but I can't access them when I use the FQDM.

e.g.

nc -v -z -w2 10.1.2.4 8080
Connection to 10.1.2.4 8080 port [tcp/*] succeeded!

nc -v -z -w2 test.eastus.cloudapp.azure.com 8080
nc: connect to test.eastus.cloudapp.azure.com 8080 port 8080 (tcp) timed out: Operation now in progress

The VMs don't resolve the FQDN to IPs within the VNET.

What are my options?

Answer 1

eastus.cloudapp.azure.com is a public DNS name which means communication routes outside of the Vnet. This means you need to add an NSG to allow traffic to port.

Image 1

If VMs are on the same VNet and you are using Azure DNS (default) then you should be able to just use the VM name.

Example:

nc -v -z -w2 VM-hostname 8080

Answer 2

the existing answer would work, or you could have a domain or a dns server inside the network or you could use Azure Private DNS for that.

Answer 3

If you are trying to access the VM with its name internally, just do a Ipconfig/all and check the results.

You can use the DNS suffix along with the VM name. If you VM name is VM1, then you need to use this FQDN: VM1.bgoptsffxguutau1f5u032sm0g.gx.internal.cloudapp.net