Historically Route53 has been pretty useless for service discovery because of the heavy rate-limiting. Something around 5 updates per second, on the whole account with a window of 60 seconds. I don't know if it's still the case but it used to be quite painful, especially when you need to scale up the number of instances quickly.
Is it that they didn't have APIs for these operations and now they do?
I know I'm missing something.
Now with auto-naming, you create a service, then a service instance calls RegisterInstance on start-up with a much simpler JSON payload.
The one time I've wanted this is with auto scaling groups for services that don't use ELBs. I haven't found docs on it, but if this could be used to add/remove DNS records based on auto scaling events that would be useful. It would save from using lifecycle hooks to trigger a Lambda function.
Also this seems to be a larger service discovery play, it just doesn't seem very fleshed out yet.
Am I right?
Only with UDP transport, longer responses are told to requery via TCP.