Which is the primary purpose of a firewall?

The primary purpose of a firewall is to protect against unauthorized access. Firewalls serve as a barrier between an internal network and external networks, monitoring and controlling incoming and outgoing network traffic based on predetermined security rules. They help prevent unauthorized users from accessing sensitive data and internal systems, ensuring that only legitimate traffic is allowed through.

In this context, firewalls are critical for establishing a secure network environment where potential threats, such as hackers or malicious software, are blocked from entering the system. By establishing these controlled points of access, firewalls enhance security and help maintain the integrity and confidentiality of the data within the network.

Other options, such as encrypting data, monitoring system performance, or preventing hardware failures, do not align with the primary function of a firewall. Encrypting data involves securing information to render it unreadable to unauthorized users, which is a separate aspect of information security. Monitoring system performance relates to assessing the efficiency and stability of computer systems but does not inherently provide protection against unauthorized access. Preventing hardware failures pertains to the reliability of physical components and is unrelated to the protective role of a firewall in network security.