What type of network device can be configured to block unauthorized access?

A firewall is specifically designed to monitor and control incoming and outgoing network traffic based on predetermined security rules. It acts as a barrier between a trusted internal network and untrusted external networks, such as the internet. By filtering data packets, a firewall can block unauthorized access attempts, protecting sensitive data and maintaining the integrity of the network.

Firewalls can be hardware-based, software-based, or a combination of both, and they offer the ability to set granular rules for what traffic is allowed or denied. This is critical in maintaining a secure network environment, particularly in preventing unauthorized users from gaining access to private or sensitive information.

In contrast, while routers and switches are important for directing traffic within a network, they do not inherently provide the same level of security features aimed at blocking unauthorized access. Routers can have some basic firewall functionality but are primarily designed for routing traffic. A hub simply broadcasts data to all devices on a network without any form of access control or filtering, making it unsuitable for securing a network.