What is the primary purpose of a firewall in network security?

The primary purpose of a firewall in network security is to monitor and control network traffic. Firewalls act as a barrier between a trusted internal network and untrusted external networks, such as the internet. They filter incoming and outgoing traffic based on predetermined security rules, which helps to protect the network from unauthorized access and potential attacks.

By analyzing packets of data being sent to and from the network, firewalls can enforce policies that determine which types of traffic are allowed through. This monitoring is crucial in maintaining the security of the network, as it allows administrators to manage vulnerabilities and respond to threats proactively. The ability of a firewall to control traffic helps ensure that only legitimate traffic can enter or leave the network, thereby reducing the risk of data breaches and other malicious activities.

Other options may seem relevant but do not capture the primary function of a firewall. Increasing network speed and improving system performance are more related to network optimization rather than security. Blocking all incoming connections is an overly simplistic view of a firewall's functionality, as some connections need to be allowed for appropriate communication, and firewalls are designed to selectively permit or deny traffic rather than simply blocking everything.