Which firewall operates at the network level and forms a perimeter for internal LAN?

The choice of a network-based firewall as the correct answer is appropriate because it is specifically designed to operate at the network layer of the OSI model. This type of firewall serves as a barrier between a trusted internal local area network (LAN) and untrusted external networks, such as the internet. By monitoring the incoming and outgoing traffic based on predetermined security rules, network-based firewalls help protect the integrity, confidentiality, and availability of the internal network.

In contrast, host-based firewalls operate on individual devices, controlling traffic for that specific host rather than providing perimeter defense. Next-generation firewalls, while they do offer capabilities beyond traditional firewalls, such as integrated intrusion prevention and application awareness, still fall under the broader category of network security devices rather than defining the fundamental operation of a firewall at the network layer. Proxy servers function differently by acting as intermediaries for client requests to external servers rather than directly controlling traffic flow between the internal and external networks.

Overall, the network-based firewall’s primary function is to manage and secure network traffic at the perimeter, making it a critical component for safeguarding the internal LAN from external threats.