Google Online Security Blog: Google Public DNS over HTTPS (DoH) supports RFC 8484 standard

Security Blog

The latest news and insights from Google on security and safety on the Internet

Google Public DNS over HTTPS (DoH) supports RFC 8484 standard

26 June 2019

Posted by Marshall Vale, Product Manager and Alexander Dupuy, Software Engineeredge PoPs

https://dns.google/dns-query (RFC 8484 – GET and POST)

https://dns.google/resolve (JSON API – GET)

We are deprecating internet-draft DoH support on the /experimental URL path and DoH service from dns.google.com, and will turn down support for them in a few months.
With Google Public DNS, we’re committed to providing fast, private, and secure DNS resolution through both DoH and DNS over TLS (DoT). We plan to support the JSON API until there is a comparable standard for webapp-friendly DoH.

What the new DoH service means for developers
To use our DoH service, developers should configure their applications to use the new DoH endpoints and properly handle HTTP 4xx error and 3xx redirection status codes.

Applications should use dns.google instead of dns.google.com. Applications can query dns.google at well-known Google Public DNS addresses, without needing an extra DNS lookup.
Developers using the older /experimental internet-draft DoH API need to switch to the new /dns-query URL path and confirm full RFC 8484 compliance. The older API accepts queries using features from early drafts of the DoH standard that are rejected by the new API.
Developers using the JSON API can use two new GET parameters that can be used for DNS/DoH proxies or DNSSEC-aware applications.

Redirection of /experimental and dns.google.com

The /experimental API will be turned down in 30 days and HTTP requests for it will get an HTTP redirect to an equivalent https://dns.google/dns-query URI. Developers should make sure DoH applications handle HTTP redirects by retrying at the URI specified in the Location header.
Turning down the dns.google.com domain will take place in three stages.

The first stage (in 45 days) will update the dns.google.com domain name to return 8.8.8.8 and other Google Public DNS anycast addresses, but continue to return DNS responses to queries sent to former addresses of dns.google.com. This will provide a transparent transition for most clients.
The second stage (in 90 days) will return HTTP redirects to dns.google for queries sent to former addresses of dns.google.com.
The final stage (in 12 months) will send HTTP redirects to dns.google for any queries sent to the anycast addresses using the dns.google.com domain.

We will post timelines for redirections on the public‑dns‑announce forum and on the DoH migration page. You can find further technical details in our DoH documentation, and if you have a question or problem with our DoH service, you can create an issue on our tracker or ask on our discussion group. As always, please provide as much information as possible to help us investigate the problem!