Which of the following is an essential product needed to secure a network?

A firewall is an essential product needed to secure a network because it acts as a barrier between a trusted internal network and untrusted external networks, such as the internet. Firewalls monitor and control incoming and outgoing network traffic based on predetermined security rules, helping to prevent unauthorized access and cyber threats. They can be hardware-based, software-based, or a combination of both and are crucial for establishing a secure network infrastructure.

While routers, modems, and servers play important roles in networking, they do not specifically provide the core security functions that a firewall does. Routers direct data traffic between networks, modems connect networks to the internet, and servers host applications and data but do not inherently provide the same level of security as firewalls. This distinction underscores the critical role of firewalls in maintaining network security.