We have decided to officially retire the rest.wikimedia.org domain in favor of /api/rest_v1/ at each individual project domain. For example,
https://rest.wikimedia.org/en.wikipedia.org/v1/?doc
becomes
https://en.wikipedia.org/api/rest_v1/?doc
Most clients already use the new path, and benefit from better performance from geo-distributed caching, no additional DNS lookups, and sharing of TLS / HTTP2 connections.
We intend to shut down the rest.wikimedia.org entry point around March, so please adjust your clients to use /api/rest_v1/ soon.
Thank you for your cooperation,
Gabriel