HTTPS RR (HTTPS Resource Records) are a type of DNS record that delivers configuration information and parameters for how to access a service via HTTPS.
An HTTPS RR can be used to optimize the process of connecting to a service using HTTPS. Further, the presence of an HTTPS RR signals that all useful HTTP resources on the origin are reachable over HTTPS, which in turn means that a browser can safely upgrade connections to the domain from HTTP to HTTPS.
- Service binding and parameter specification via the DNS (DNS SVCB and HTTPS RRs) (Draft IETF specification: draft-ietf-dnsop-svcb-https-00)
- Strict Transport Security vs. HTTPS Resource Records: the showdown (Emily M. Stark blog)