What is the primary function of a firewall?

The primary function of a firewall is to block unauthorized access to or from a private network. Firewalls serve as a security barrier, monitoring and controlling incoming and outgoing network traffic based on predetermined security rules. They help protect private networks from external threats and unauthorized access attempts, effectively preventing potential intrusions or attacks. By filtering the traffic, firewalls can allow only trusted communications and deny potentially harmful connections, ensuring the integrity and security of the data and systems within the network.

The other options do not align with the core purpose of what a firewall does. Improving internet speed is not a function of a firewall, as it primarily focuses on security. Managing system memory relates to how the operating system handles available resources and is not relevant to a firewall's role. Likewise, while software updates are crucial for maintaining system security and functionality, they are not an active role played by firewalls—they are instead a task performed by the software on the devices themselves.