plan 9 dns tries to look up unrooted (no ".") names in the local databases.
first success wins.

here's the algorithm from /sys/src/cmd/ndb/dnresolve.c

/*
* hack for systems that don't have resolve search
* lists. Just look up the simple name in the database.
*/
if(!rooted && strchr(name, '.') == nil){
rp = nil;
drp = domainlist(class);
for(nrp = drp; rp == nil && nrp != nil; nrp = nrp->next){
snprint(nname, sizeof nname, "%%s.%%s", name,
nrp->ptr->name);
rp = dnresolve(nname, class, type, req, cn, depth+1,
recurse, rooted, status);
rrfreelist(rrremneg(&rp));
}
if(drp != nil)
rrfreelist(drp);
procsetname(procname);
free(procname);
return rp;
}

- erik