You don't need that. TTL zero and dns query header IDs are enough. You could even implement a threaded chat, using the id as a responded-to sorting mechanism.

You don't need that. TTL zero and dns query header IDs are enough. You could even implement a threaded chat, using the id as a responded-to sorting mechanism. Also, TXT can contain binary data, and when using DNS over TCP is pretty much unlimited in frame size.