(ISC)2 Certified in Cybersecurity Practice Exam

A firewall is a critical component in network security designed primarily to prevent unauthorized access to or from a private network. It acts as a barrier between a trusted internal network and untrusted external networks, such as the internet. Firewalls are configured with rules that dictate the types of traffic that are allowed or disallowed. This helps to ensure that only legitimate traffic can pass through, significantly reducing the risk of cyber-attacks and unauthorized access.

While the other options may pertain to important aspects of network security, they do not align with the primary function of a firewall. Providing data backups is vital for disaster recovery but is unrelated to access control. Scanning for viruses is a function typically performed by antivirus software, which focuses on detecting and removing malware rather than managing traffic between networks. Boosting network speed may be a concern for network performance, yet it does not relate to the essential function of a firewall to safeguard against unauthorized access and ensure that only authorized communication occurs within the network.