Setting up a VLAN on my pfSense

I'm setting up a VLAN for a lab Proxmox cluster. I've defined a DMZ (igc1) and a VLAN (OPT2 igc1.30). So far so good. Would I **not** setup a DNS server on the DMZ igc1 and instead set it up on the VLAN interface? I can think of any good reason to have two different networks subnets here.

Maybe there is a good reason like if something goes in the DMZ that is not VLAN aware it'll still get an IP so I can access it for setup?