Here’s how to setup a netmask while creating a zone:
# zonecfg -z testzone
testzone: No such zone configured
Use ‘create’ to begin configuring a new zone.
zonecfg:testzone> create
zonecfg:testzone> set zonepath=/zones/testzone
zonecfg:testzone> set autoboot=true
zonecfg:testzone> add net
zonecfg:testzone:net> set physical=hme0
zonecfg:testzone:net> set address=10.10.10.1/24
zonecfg:testzone:net> end
zonecfg:testzone> verify
zonecfg:testzone> exit
#
If you want to set a non default netmask you can replace that the following:
zonecfg:testzone:net> set address=10.10.10.1/24
Now you have set the netmark to be 255.255.255.0
There are various online tools to help you calculate the netmask number