>1) resolv.conf(5) suggests that on a 'normally configured' machine, you
>shouldn't need a resolv.conf at all.  Of course, this isn't quite true, as
>if you don't have a resolv.conf, the system assumes you don't have DNS and
>only uses /etc/hosts.

Does it say that?  Ugh.  Nearly all machines connected to the Internet
should have a resolv.conf.  I would almost call that a bug :-)

>2) resolv.conf(5) says that if there is no domain directive, the domain is
>set to everything after the first dot in the hostname.  This implies that
>the hostname of my machine should by elsie.mailbox.co.uk, rather than
>'elsie' which is what it is now.  However... if /etc/myname is used to
>initialise hostname to elsie.mailbox.co.uk, then what should be in
>/etc/defaultdomain??  And will elsie.mailbox.co.uk then appear in my prompt
>etc?  Are hostnames supposed to be FQ or not?

Hostnames being FQ is one of those religious arguments.  Personally, I
never fully qualify hostnames on my machines - I think it looks ugly.  But
some people prefer it that way.  I don't think you need /etc/defaultdomain
at all -  I don't have one.  I do have a domain directive in my resolv.conf.

>3) If there is a nameserver 127.0.0.1 directive in resolv.conf, then when
>nslookup is invoked, it says "Default server: localhost\nAddress:
>127.0.0.1".  If there is no such directive, or no resolv.conf file at all,
>it says "Default server: elsie\nAddress 0.0.0.0".  Which is preferred
>behaviour?

0.0.0.0 is another alias for localhost - either one will be fine.  I
set mine to 127.0.0.1, but 0.0.0.0 may be more correct.

>4) If I just want my machine to serve as a name-cache for a small local
>network, it should have no primary or secondary directives in named.boot,
>right?

Weeeeellll .... I put secondary directives for frequently used networks
(for example, the domain I'm in).  This really speeds up DNS lookups,
and has another advantage (see below).

>5) This machine is not permanently on the net - it is connected by a PPP
>link.  Should I put the resolver down every time I hang up the link (e.g.
>in /etc/ppp/ip-down)?  This prevents my macintosh on the network from
>looking even local names, since they have to use DNS.

If you become an "unofficial secondary" for the domain you're in, you'll
always have a copy of the DNS zones that your machines live in, and DNS
will work locally even when you're off the net.  Note that you'll need
to do both the forward and reverse domains (in-addr.arpa) to benefit
from this.

--Ken