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

Before you begin

• If you haven't already, set upauthentication. 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:

  Console

  When you use the Google Cloud console to access Google Cloud services and APIs, you don't need to set up authentication.

  gcloud

  1. Install the Google Cloud CLI. After installation,initialize the Google Cloud CLI by running the following command:

     gcloudinit

     If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

     Note: If you installed the gcloud CLI previously, make sure you have the latest version by runninggcloud components update.
  2. Set a default region and zone.

  REST

  To use the REST API samples on this page in a local development environment, you use the credentials you provide to the gcloud CLI.

  Install the Google Cloud CLI. After installation,initialize the Google Cloud CLI by running the following command:

  gcloudinit

  If you're using an external identity provider (IdP), you must first sign in to the gcloud CLI with your federated identity.

  Note: If you installed the gcloud CLI previously, make sure you have the latest version by runninggcloud components update.

  For more information, seeAuthenticate for using REST in the Google Cloud authentication documentation.

Determine the internal DNS name for a VM

Use the following procedure to read the internal DNS name assigned to a VMinstance. You can get the internal DNS name by querying thehostname metadataentry.

1. Connect to the VM.

2. Query thehostname 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

Access VMs by internal DNS name

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

The following example usesping to contact a VM that useszonal DNS. This method works, providedthat you have created afirewall rule that allowsincoming ICMP traffic to the instance.

$pingVM_NAME.ZONE.c.PROJECT_ID.internal -c 1PINGVM_NAME.ZONE.c.PROJECT_ID.internal (10.240.0.17) 56(84) bytes of data.64 bytes fromVM_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 tozonal DNS
• Learn more aboutinternal DNS names for Compute Engine.
• Configure static IP addresses for your VM.