hostname.interface_name
hosts
defaultrouter
netmasks
nodename
还需要更改/etc/inet/ipnodes
Note –
If you need to add addresses, you must add IPv4 addresses to both the hosts and ipnodes files. You add only IPv6 addresses to the ipnodes file.

Address search order is ipnodes first, then hosts. (solaris 8, 9, 10)
So ipnodes needn@#t be modified if it@#s no information about IPv4 address.

But in Solaris 10, a new feature added:

The /etc/nsswitch.conf file policies for the hosts database and ipnodes repositories are synchronized.

In your case, hosts changed but ipnodes untouched so that
system got old ip address from ipnodes.