Network security

A firewall inspects traffic crossing a network boundary and applies rule sets to allow, block, or limit connections based on source, destination, port, and protocol. While routers also forward packets, they typically do not enforce granular security policies. Switches operate at Layer 2 and hubs simply repeat signals, offering no policy enforcement capabilities.

A Web Application Firewall (WAF) operates at Layer 7 of the OSI model, allowing it to inspect HTTP/HTTPS traffic to block web-specific exploits like SQL injection and XSS. In contrast, network-layer firewalls (Option A) inspect lower-level traffic properties like IP addresses and ports, making them blind to application-payload attacks.

A VPN secures network traffic primarily by creating an encrypted tunnel that protects data in transit from eavesdroppers. A diagram for this topic isn't available yet — the worked example below walks the same reasoning step by step.

• !Option A is incorrect because firewall rules control incoming and outgoing traffic based on security policies, rather than encrypting the communication channel itself.
• !Option C is incorrect because a DMZ is a network architecture design, not a physical firewall device itself.
• !While routers also forward packets, they typically do not enforce granular security policies.
• !It is commonly used to secure VPN connections.

Answer each from memory — you'll see instantly whether you're right and why.

Run a focused 10-question mini-mock on Network security and see it stick.