Google Public DNS now auto-detects nameservers that support edns-client-subnet

[Shen Wan]

Dear users and nameserver owners,

We are pleased to announce that Google Public DNS now automatically detects nameservers that support edns-client-subnet (ECS) options as defined in the IETF draft, and will send queries with ECS options to such nameservers automatically.

This is implemented by probing nameservers at a low rate with ECS queries and caching the ECS capability for each nameserver. Therefore if your nameservers do not support ECS, they may still receive a few ECS queries occasionally. And if your nameservers just started to support ECS, it may take us several hours to detect the change and start to send ECS queries to them.

Please note that we only support ECS options with the official EDNS0 option code (8) now. If your nameservers are still using the experimental code (20730 or 0x50FA), please switch to the official code.

If your nameservers support ECS but do not receive ECS queries from us, please submit a ticket at https://code.google.com/a/google.com/p/public-dns/issues/entry. Please include the nameserver IP addresses and a test domain name so that we can debug the issue.

Thanks,
Shen