COMPUTER NETWORKING

Detailed explanation-1: -A circuit-level gateway is a type of firewall that operates on layer 5 of the Open Systems Interconnection (OSI) model, which is the session layer.

Detailed explanation-2: -Proxy firewalls filter traffic at the application layer, which is Layer 7 of the Open Systems Interconnection model.

Detailed explanation-3: -Firewalls typically work on the network layer, the transport layer. However, some are also capable of working as high as the application layer, Layer 7.

Detailed explanation-4: -–Circuit-level proxy Operates at the Session Layer of the OSI Model and makes access decisions based on address, port and protocol type, and not on the packet content. This firewall creates a circuit between the client computer and the server.

Detailed explanation-5: -Packet-filtering firewalls operate at the network layer (Layer 3) of the OSI model. Packet-filtering firewalls make processing decisions based on network addresses, ports, or protocols. Packet-filtering firewalls are very fast because there is not much logic going behind the decisions they make.