DHCP Scope

Hi,

Currant setup , I have with server 2003 DHCP + DNS setup as listed.
Scope
192.168.100.1 to 192.168.100.254
255.255.255.0 – Sub net Mask
192.168.100.1 ( Router ??? Sonic wall ) ( Default Gateway for All member server + Client )
192.168.100.8 ( Domain server + ADC )

Issue : Problem of Dwindling IP addresses ( this scope All IP useed it’s give error of 90 % IP used )

Questions :
how to setup 2nd scope with new IP range E.g. 192.168.101.1 to 254 ? sub net same ? how to setup like not make any major change in other setup & get new IP range in exits setup.