Which describes how firewalls operate?

• A. They encrypt all traffic by default.
• B. They inspect messages and block those not meeting security criteria.
• C. They are used to manage user accounts.
• D. They automatically scan for viruses.

Answer: (B)

Firewalls act as gatekeepers at the network boundary by filtering traffic based on security rules. They examine each message or packet, compare it to configured criteria (such as where it’s coming from, where it’s going, and what type of traffic it is), and then allow or block it accordingly. This selective filtering is what keeps unwanted access out while permitting legitimate communications.

Encryption by default isn’t the firewall’s primary job—encryption is handled by protocols and services like TLS or VPNs, and a firewall may pass encrypted traffic but doesn’t automatically encrypt all data. Managing user accounts is the realm of identity and access management, not firewalls. Virus scanning is typically the job of antivirus software or security gateways, not the firewall’s main function.