doctl author here. The server isn't unknown, that's its name. This project was a private effort, and this component will be migrated to TLS and a DO domain on Monday. In the mean time, you can create a configuration file at $HOME/.doctlcfg (which is yaml formatted) and add an entry `access-token: <your access token>`, and you won't need to run `doit auth login`.
whois[1] says the registrant's name is Bryan Liles, which is the name of a Digital Ocean employee[2].