Use ifconfig to change the IP address immediately

ifconfig    

If the new IP address calls for a different gateway then change it using the route command:

route add default 
route del default 
 

Change the hosts’s IP address in

• /etc/hosts file to take effect after each reboot
• /etc/inet/ipnodes (for Solaris 10)

Change the host’s subnet mask in /etc/netmask

Change the host’s default gateway in /etc/defaultrouter