I’ve recently been caught out whilst trying to change the IP on a Solaris 10 machine. It used to be the /etc/hostname.pcn0 (or whatever type of interface it was) had o match the entry in /etc/hosts. Now it seems this isn’t the only place you need to make the change, you also need to change the IP in /etc/inet/ipnodes as-well, which is the same format as /etc/hosts