Answer:
Firewall should be placed between Internal Zone and DMZ. It is also placed between External Zone and DMZ.
Step-by-step explanation:
To add the additional features of security in an organization's internal network to make it secure from hackers attacks and unnecessary access from unauthorized users a DMZ (demilitarized Zone) has been established between organization's Network that could be LAN and outside Networks exist on Internet. This zone has two firewalls to check the access resources and information of the users from outside the organization by double check. In this type of network, external users cannot access the LAN network directly.
There are two different zones in this type of network: Internal Zone and External Zone. A firewall is installed between internal Zone and DMZ to monitor the traffic from DMZ to internal network of the organization. The other Firewall is placed between External zone and DMZ to monitor the external traffic between DMZ and External Network at internet.