A VLAN can be a DMZ. This is just a virtual separation of different networks inside one hardware-network-environment. So for example you can have different networks within one switch. That a DMZ is realized with a VLAN or by separation with different hardware doesn't matter for the concept.

Does a DMZ need its own VLAN?

Your DMZ should have its own separate switch, as should the internal network and the external network; you should not use VLAN partitioning to create these networks. ... If you want to deploy multiple DMZs, you might use VLAN partitioning to separate the DMZs, all of which are connected to the same switch.

What is an example of a DMZ?

The DMZ Network exists to protect the hosts most vulnerable to attack. These hosts usually involve services that extend to users outside of the local area network, the most common examples being email, web servers, and DNS servers.