On Tue, 29 Jul 2008, Steven M. Bellovin wrote:
On Tue, 29 Jul 2008 15:56:19 +0200
Colin Alston <[EMAIL PROTECTED]> wrote:
DNS uses UDP.
Ahh yes of course..
Why does it use UDP? :P
In this situation, UDP uses one query packet and one reply. TCP uses 3
to set up the connection, a query, a reply, and three to tear down the
connection. *Plus* the name server will have to keep state for
every client, plus TIMEWAIT state, etc. (Exercise left to TCP geek
readers: how few packets can you do this in? For example -- send the
query with the SYN+ACK, send client FIN with the query, send server FIN
with the answer? Bonus points for not leaving the server's side in
TIMEWAIT. Exercise for implementers: how sane can your stack be if
you're going to support that?)
It was advocated as T/TCP in 90s.
http://www.kohala.com/start/ttcp.html
Not accepted widely:
http://en.wikipedia.org/wiki/T/TCP
Regads,
Janos Mohacsi
