Which of the following devices acts as a barrier between your internal network and external threats?

The device that acts as a barrier between your internal network and external threats is a firewall. A firewall monitors and controls incoming and outgoing network traffic based on predetermined security rules. By doing so, it effectively establishes a barrier between a trusted internal network and one that is untrusted or potentially harmful, such as the internet. The primary role of a firewall is to allow or block traffic based on security policies, thereby preventing unauthorized access and protecting sensitive data from external attacks.

In contrast, while routers, switches, and modems perform essential networking functions, they do not inherently provide security against external threats. A router directs data packets between networks, a switch connects devices within a single network to enable communication, and a modem modulates and demodulates signals for internet connectivity. None of these devices specifically focus on filtering threats and enforcing security protocols as a firewall does, highlighting the unique protective function of the firewall in a cybersecurity framework.