Certified Information Systems Auditor (CISA) — Question 604

Which of the following types of firewalls provide the GREATEST degree of control against hacker intrusion?

Answer options

• A. Packet filtering router
• B. Circuit gateway
• C. Application level gateway
• D. Screening router

Correct answer: C

Explanation

The Application level gateway, also known as a proxy firewall, inspects the data at the application layer, which allows it to provide more comprehensive filtering and control over traffic compared to the other types. Packet filtering routers and screening routers only analyze headers and established connections, while circuit gateways operate at the transport layer, making them less effective against complex intrusion attempts.