Subject: DNS HTTPS/SVCB record type support in iOS 14

From: Tommy Pauly <[email-masked]>
Date: Fri, 25 Sep 2020 12:58:26 -0700

Hello DNSOP & QUIC,

I wanted to provide an update that the production version of iOS 14, which shipped last week, includes support for sending HTTPS (SVCB) DNS queries (RR type 65) for applications using our system networking APIs.

The implementation status has been updated here: https://github.com/MikeBishop/dns-alt-svc/blob/master/svcb-implementations.md <https://github.com/MikeBishop/dns-alt-svc/blob/master/svcb-implementations.md>

For those with HTTP/3 QUIC deployments, this means that (when HTTP/3 experimental support is enabled) iOS will use the ALPN indication in the HTTPS record to enable HTTP/3 prior to receiving an Alt-Svc indication. As previously noted on the DNSOP list, Cloudflare is already supporting publishing these records, and we’d encourage other server deployments that support QUIC to do the same.

To note, this behavior is the same in the betas of macOS 11.

Best,
Tommy