Palo Alto Networks (PANW) Certified Cybersecurity Entry-level Technician (PCCET) Practice Exam

Which type of firewall operates up to Layer 4 (transport layer) of the OSI model and inspects individual packet headers to determine source and destination IP address, protocol (TCP, UDP, ICMP), and port number?

1. Proxy

2. Application

3. Packet filtering

4. Stateful inspection

The correct answer is: Packet filtering

The type of firewall that operates up to Layer 4 (the transport layer) of the OSI model and inspects individual packet headers is indeed a packet filtering firewall. This firewall performs a basic level of traffic analysis by examining header information for each packet, including the source and destination IP addresses, the transport layer protocol (such as TCP, UDP, or ICMP), and the port numbers associated with these protocols. Packet filtering firewalls make decisions based on predefined rules set by the administrator. They allow or block traffic based on the factors mentioned, without retaining any context of the traffic flow or establishing state information; rather, they treat each packet independently. This method can effectively block unwanted traffic and ensure that the packets align with the security policies defined. In contrast, other types of firewalls, such as proxy firewalls and application firewalls, operate at different layers of the OSI model and include more advanced capabilities like traffic analysis, stateful inspection, or content filtering. Proxy firewalls, for instance, work at the application layer and can inspect the entire content of traffic, while stateful inspection firewalls maintain state information about active connections, allowing for more sophisticated decisions based on the context of traffic flows.