Okay suppose you are on a corporate LAN and VPN’d into some other private network. You want DNS to resolve the local intranet, but also resolve your VPN’d LAN. If you VPN’d LAN domain is internal.sollicker.com then create;

/etc/resolver/sollicker.com

and in this file;

search internal.sollicker.com sollicker.com

nameserver 172.16.100.15

Then run:

sudo kill -HUP `cat /var/run/lookupd.pid`