What is the main function of an Intrusion Detection System (IDS)?

An Intrusion Detection System (IDS) primarily focuses on monitoring network traffic for any signs of suspicious or malicious activities. Its main function is to analyze incoming and outgoing traffic to identify behaviors that resemble known threats, which can indicate attempts to breach security or exploit vulnerabilities. The IDS serves as a tool for detection and alerting; it notifies administrators about potential intrusions so they can take appropriate action.

The other options pertain to different security functions. Blocking incoming threats is the primary role of an Intrusion Prevention System (IPS), which actively intervenes to stop attacks. Encrypting sensitive data in transit is handled by encryption protocols rather than an IDS, which does not contribute to this aspect of data security. Performing regular backups is a part of data protection strategies and recovery plans but is not associated with the functionalities of an IDS. Hence, monitoring for suspicious activities distinctly characterizes the main function of an IDS in a network security context.