Each instance’s metadata server acts as a DNS server. It stores the DNS entries for all VPC network IP addresses in the local VPC network and calls Google’s public DNS server for entries outside the VPC network. You cannot configure this DNS server. The DHCP client on each instance is configured to manage the instance’s /etc/resolv.conf file.

You can add your own search domain or nameservers to the instance’s /etc/resolv.conf by modifying the DHCP policy. Many Linux distributions allow these modifications to persist via /etc/dhcp/dhclient.conf. See the Internal DNS documentation for more information.