Question

A packet filter firewall filters at __________

(a) Physical layer

(b) Data link layer

(c) Network layer or Transport layer

(d) Application layer

This question was addressed to me by my college director while I was bunking the class.

This key question is from Firewalls topic in portion Network Layer of Computer Network

Answer 1

Right answer is (c) Network layer or Transport layer

Explanation: In computing, a firewall is a network security system that monitors and controls the incoming and outgoing network traffic based on predetermined security rules.[1] A firewall typically establishes a barrier between a trusted, secure internal network and another outside network, such as the Internet, that is assumed not to be secure or trusted.[2] Firewalls are often categorized as either network firewalls or host-based firewalls.