512 byte limit

[Mark Andrews]

In message <46e76f620901210952s3a357724w44e08804484fb2e7 at mail.gmail.com>, Josh 
Kuo writes:
> > 1) If a reply is over 512 bytes, which can't in theory be done via UDP,
> > should the queried server reply telling my resolver to ask again using
> > TCP?  Assuming, as one normally should, that there are firewalls, the
> > queried server can't simply reply TCP, as it would get blocked.
> 
> I am not sure about the UDP size question, but I am pretty sure this
> is a client behavior, i.e. the server does not send back a reply to
> tell the client to use TCP port, but client should try UDP, fails, and
> switch to using TCP.

	Correction, the server sends back a UDP reply with TC set in the
	flags.  The client then initiates a TCP based query.  Please
	read RFC 1034 and RFC 1035.

	Mark
> _______________________________________________
> bind-users mailing list
> bind-users at lists.isc.org
> https://lists.isc.org/mailman/listinfo/bind-users
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: Mark_Andrews at isc.org