What is the primary function of firewalls?

The primary function of firewalls is to prevent unwanted internet traffic. Firewalls serve as a security barrier between a trusted internal network and untrusted external networks, such as the internet. They analyze incoming and outgoing traffic based on predetermined security rules and help to block unauthorized access, thus protecting systems from external threats such as malware, hacking attempts, and other malicious activities. By doing so, they ensure that only legitimate traffic is allowed through, enhancing the security of the network.

Other options, such as speeding up internet access or monitoring employee productivity, do not align with the main role of a firewall. While it may seem that enhancing system performance is related, firewalls specifically focus on traffic security rather than optimizing performance. The key purpose remains firmly rooted in controlling and securing network traffic, making the prevention of unwanted internet traffic the correct answer.