[dns-operations] Random question about Google resolver behaviour and long-lived TCP sessions

Alexander Dupuy alexdupuy at google.com
Fri Sep 27 16:19:24 UTC 2019

Tony Finch wrote:
> So I wonder if Google have implemented EDNS TCP keepalive. If you change
> what BIND calls tcp-advertised-timeout, do Google's TCP connection
> lifetimes change to match?

Google Public DNS has not implemented EDNS TCP keepalive, neither as a
server for its clients, nor in its TCP connections to authoritative
servers. Has BIND added support on its client side, or only as a DNS
server? It seems like Unbound has client and server-side support (
https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=231283), and the GetDNS
client code also supports it (https://getdnsapi.net/releases/getdns-0-9-0/)
but those are the only ones I found. I don't see any implementations of RFC
8490 (DNS Stateful Operations).

In any case, as I wrote before, the TCP connections Jake is seeing are not
from Google Public DNS, and quite possibly not even DNS at all (let alone

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