North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: Great Suggestion for the DNS problem...?
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?) --Steve Bellovin, http://www.cs.columbia.edu/~smb
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