Which component primarily serves to protect a network from unauthorized access?

The component that primarily serves to protect a network from unauthorized access is a firewall. Firewalls are designed to enforce security policies by monitoring and controlling incoming and outgoing network traffic based on predetermined security rules. They act as a barrier between a trusted internal network and untrusted external networks, such as the internet, effectively blocking malicious traffic and preventing unauthorized access attempts.

By examining packets and determining whether to allow or deny traffic based on various criteria, firewalls can help prevent intrusions, data breaches, and other security threats. They can be implemented in hardware, software, or as a combination of both.

In contrast, routers primarily direct data between networks and can include limited firewall capabilities, while switches operate at a more local level to connect devices within a single network segment without focusing on security. Modems function to connect a network to the internet but do not inherently provide security against unauthorized access.