What does an air gap prevent in network security?

An air gap is a security measure that physically separates a secure network from other networks, particularly from the internet or any potentially untrusted networks. By creating a physical separation, an air gap prevents unauthorized access from external networks, effectively shielding sensitive data and systems from external threats such as hacking, malware, and other forms of intrusion.

This isolation ensures that even if the external network is compromised, there is no direct path for an attacker to access or manipulate data within the air-gapped network. It serves as a robust defense mechanism for highly sensitive information, often utilized in environments such as government agencies, critical infrastructure, and financial institutions.

In contrast, the other options focus on issues that are not directly addressed by an air gap. For example, while data loss due to server failure is a concern that can be mitigated through backups and redundancy, it is not something that air gaps specifically protect against. Similarly, interference from internal network traffic or overuse of network resources relate to network management and performance rather than security against unauthorized external access. Therefore, the most fitting description of what an air gap prevents is unauthorized access from external networks.