Excerpts from netbsd: 30-Oct-98 Re: TCP NFS mounts of swap/.. Frank van
der Linden@win (411*)

> > : It already does that. It's an option because some people may not want
> > : their roots be TCP, even if it's available.
> > 
> > In that case, the option (enabled) should be in all GENERICs (and SHARK,
> > etc.).
> 
> Not quite. It should be in there, but disabled, to be consistent to
> the normal mount interface, which also uses UDP by default.

I once compared the NFS performances and found UDP
transport slightly faster than TCP (on a local, non-lossy network).
So I don't use TCP even if available.
And: You can change it later via "mount -u".

best regards
Matthias