DNS UDP or TCP?

[Cricket Liu]

> >  Actually, there are (or have been) some resolvers that use
> >  TCP by default.  I think an older AIX resolver fell into this
> >  category, as did the resolver on the HP1000.
> 
> Really?  I had absolutely no idea.  Man, this just further 
> illustrates how dain-bramaged people really are when they block all 
> TCP to port 53, thinking that this will keep them secure from having 
> their entire zone transferred.  Sigh....

Yeah.  The HP1000 didn't have a UDP implementation at one point,
just TCP.  So Todd Poynor, who implemented the HP1000's resolver,
wrote it to run over TCP.

Wild, huh?

Of course, there probably aren't that many people with HP1000s
querying their name servers, but I'll bet there are still a few out there.

cricket

Men & Mice
DNS Software & Services
www.menandmice.com