After [yet another question][1] asking how to bring hostname-awareness for proxying purposes to a protocol that doesn't have any support for it, is it time for a [canonical][2] question on hostname-aware proxying, plus a good answer on how DNS works, the few protocols that *are* hostname-aware and how they do it, and the impossibility of a general solution for all other protocols?  I'm happy to take a stab at a short question, and longer answer, but wanted to take your minds on whether it was desirable before so doing.

**Edit**: thanks to HBruijn and upvoters for support, and especially to kasperd for some excellent suggestions.  The QA now appears [here][3], and people should feel free to amend/vote/mock as appropriate.  I'll add it to the canonical canonical answer shortly.


  [1]: https://serverfault.com/q/876993/55514
  [2]: https://meta.serverfault.com/questions/1986/what-are-the-canonical-answers-weve-discovered-over-the-years
  [3]: https://serverfault.com/q/878080/55514