If the DMZ interface is connected to a switch create sub-interfaces and setup the switch port for do1q trunking.
interface GigabitEthernet0/3
description DMZ Interface
speed 100
duplex full
no nameif
no security-level
no ip address
no shut
interface GigabitEthernet0/3.20
description DMZ Subnet 1
vlan 20
nameif DMZ1
security-level 50
ip address X.X.X.X X.X.X.X
interface GigabitEthernet0/3.30
description DMZ Subnet 2
vlan 30
nameif DMZ2
security-level 50
ip address X.X.X.X X.X.X.X
Thanks,
Chad
Please rate if helpful!