[dns-operations] EDNS buffer size on TCP connections?

[David C Lawrence]

bert hubert writes:
> While working on a PowerDNS bug, I wondered: what do I fill out on the
> buffer size field of the EDNS record on a TCP/IP connection?

In client requests it is in effect ignored by the DNS/TCP
implementations with which I am familiar because it is explicitly
defined as the UDP payload size.

A responder can still set it to the maximum payload size it would
support for future UDP transactions.