dan bernstein (do qmail fame) tem um site dedicado a escolher um dnsname para a rede local ( link ):
It isn't easy to choose a safe top-level local name. The global root
operators add new top-level names every once in a while: for example,
.info was added in 2001, so people using .info as a local name were
unable to reach global .info sites. Software authors sometimes set
aside top-level names; for example, I'm told that Mac OS 9 does something
weird with .local, so it can't access local names in .local. Here are
some reasonable choices of top-level local names:
.0 (good for machine-specific names)
.1
.2
.3 (good for department-specific names)
.4
.5
.6 (good for corporation-specific names)
.7
.8
.9
.internal