What is the primary role of a firewall in a network?

• A. A firewall filters traffic between networks.
• B. A firewall assigns IP addresses.
• C. A firewall routes packets.
• D. A firewall translates domain names.

Answer: (A)

The main idea here is that a firewall’s job is to control access by examining and filtering traffic as it moves between networks. It applies security rules to each packet or session, checking factors like where the traffic is coming from, where it’s going, what protocol or port is used, and sometimes the content of the traffic, to decide whether to allow or block it. This centralized filtering at the network boundary is what keeps undesired or risky communications from reaching protected systems while permitting legitimate traffic.

Other functions are roles for different devices: assigning IP addresses is handled by DHCP, routing packets through a network is the job of a router, and translating domain names is done by DNS resolvers. Some features might overlap in advanced firewalls (like DNS filtering or NAT in certain contexts), but the core purpose remains filtering traffic between networks.