Cloud DNS

Compute Engine VM instances use their metadata servers as internal DNSs to resolve the IP addresses of other VMs in the same network. A metadata server communicates with Google’s public DNS for queries outside a local network. For example, the following figure shows an SSH session to a Compute Engine VM, vm-a, during which it resolves the external address, google.com, even though, as in this case, it doesn’t have access to the internet. Also, it can resolve an address of another VM, vm-b, because it is in the same network and, in this case, the same subnet and zone. The fully qualified domain name (FQDN) of VMs is vm_name.zone.c.project_id.internal internally:

Figure 9.27 – Local metadata server acting as a DNS for a Compute Engine VM

As a metadata server can only resolve addresses for VMs in the same network and users can’t edit their configuration, for more advanced architectures that scale outside a VPC network...