Which of the following would be the MOST secure firewall system?

A.
Screened-host firewall

B.
Screened-subnet firewall

C.
Dual-homed firewall

D.
Stateful-inspection firewall

Explanation:
A screened-subnet firewall, also used as a demilitarized zone (DMZ), utilizes two packet filtering routers and a
bastion host. This provides the most secure firewall system, since it supports both network- and applicationlevel security while defining a separate DMZ network. A screened-host firewall utilizes a packet filtering router
and a bastion host. This approach implements basic network layer security (packet filtering) and application
server security (proxy services). A dual-homed firewall system is a more restrictive form of a screened-host
firewall system, configuring one interface for information servers and another for private network host
computers. A stateful-inspection firewall working at the transport layer keeps track of the destination IP address
of each packet that leaves the organization’s internal network and allows a reply from the recorded IP
addresses.