What is an intrusion detection system (IDS)?

An intrusion detection system (IDS) is a critical component of network security that serves to monitor network activities for potential threats or malicious behavior. This system analyzes traffic patterns and data flows to detect unauthorized access or breaches, which can indicate security incidents. The importance of an IDS lies in its ability to provide real-time alerts concerning abnormal activities that could compromise network integrity, thereby allowing organizations to respond quickly to those threats.

The other options do not align with the primary function of an IDS. A system for backing up data focuses on preserving data rather than actively monitoring for security threats. A device that encrypts data packets is concerned with protecting data through encryption, ensuring confidentiality, but does not involve monitoring or detection of intrusions. Similarly, a protocol for secure data transmission pertains to the methods used to transmit data securely over existing networks but does not involve threat detection or monitoring functionalities. Therefore, the essence of an IDS is accurately captured by identifying it as a software that specifically monitors network activities for threats.