Linux Windows

VMs in the same Virtual Private Cloud network can access each other by using internal DNS names instead of IP addresses.

Before you begin

• If you haven't already, set up authentication. Authentication verifies your identity for access to Google Cloud services and APIs. To run code or samples from a local development environment, you can authenticate to Compute Engine by selecting one of the following options:

  Select the tab for how you plan to use the samples on this page:

Determine the internal DNS name for a VM

Use the following procedure to read the internal DNS name assigned to a VM instance. You can get the internal DNS name by querying the hostname metadata entry.

1. Connect to the VM.

2. Query the hostname metadata:

   Linux VMs

   curl "http://metadata.google.internal/computeMetadata/v1/instance/hostname" \
     -H "Metadata-Flavor: Google"
   

   Windows VMs

   Invoke-RestMethod `
     -Headers @{"Metadata-Flavor" = "Google"} `
     -Uri "http://metadata.google.internal/computeMetadata/v1/instance/hostname"
   

The metadata server returns the VM's hostname in one of the following formats, which shows the type of internal DNS name that the VM uses:

• Zonal DNS: VM_NAME.ZONE.c.PROJECT_ID.internal
• Global DNS: VM_NAME.c.PROJECT_ID.internal

In the output:

• VM_NAME: the name of the VM
• ZONE: the zone where the VM is located
• PROJECT_ID: the project to which the VM belongs

To access the VM, use the internal DNS name in place of the IP address.

The following example uses ping to contact a VM that uses zonal DNS. This method works, provided that you have created a firewall rule that allows incoming ICMP traffic to the instance.

$ ping VM_NAME.ZONE.c.PROJECT_ID.internal -c 1

PING VM_NAME.ZONE.c.PROJECT_ID.internal (10.240.0.17) 56(84) bytes of data.
64 bytes from VM_NAME.ZONE.c.PROJECT_ID.internal (10.240.0.17): icmp_seq=1 ttl=64 time=0.136 ms

Replace the following:

• VM_NAME: the name of the VM
• ZONE: the zone where the VM is located
• PROJECT_ID: the project to which the VM belongs

What's next

• Migrate to zonal DNS
• Learn more about internal DNS names for Compute Engine.
• Configure static IP addresses for your VM.