On which of the following should a firewall be placed?

A.
Web server

B.
Intrusion detection system (IDS) server

C.
Screened subnet

D.
Domain boundary

Explanation:

A firewall should be placed on a (security) domain boundary. Placing it on a web server or
screened subnet, which is a demilitarized zone (DMZ), does not provide any protection. Since
firewalls should be installed on hardened servers with minimal services enabled, it is inappropriate
to have the firewall and the intrusion detection system (IDS) on the same physical device.