> Instead UDP is the way to go when you don't need a transport layer at all, and you can do with trivial ack / resend strategy (DNS is the obvious example), or just best-effort transfers where packet loss is not an issue at all (think a thermometer sending readings every second)
That depends I guess. As somebody who works mostly with cloud telephony, SIP (signaling) and RTP (audio) are almost always carried over UDP. Funny thing is that you'll see more occurrences of one-way audio or call drops because of people implementing the application level protocol like SIP wrong rather than the transport layer letting you down.
That said, I would any day prefer a private MPLS network rather than the public internet.
Though I can understand why somebody who writes a fast nosql database prefers TCP. Also, thanks for redis, we use it a lot and love it! :)