What does an Intrusion Detection System (IDS) do?

An Intrusion Detection System (IDS) is designed to monitor network traffic for indications of suspicious activity or security breaches. It analyzes incoming and outgoing traffic to identify patterns or anomalies that may suggest an intrusion or attack, such as unauthorized access attempts or unusual behavior from devices on the network. By actively monitoring this traffic, an IDS can alert administrators to potential threats, allowing them to respond accordingly to protect network integrity.

The other options do not accurately describe the primary function of an IDS. Encrypting data is a different process aimed at protecting confidentiality but does not involve monitoring for threats. Blocking unauthorized access pertains to the function of firewalls or Intrusion Prevention Systems (IPS), which take proactive measures to stop attacks rather than just detect them. Lastly, storing logs of user activity, while important for forensic analysis and auditing, is not the core function of an IDS; rather, it focuses specifically on detection and alerting based on traffic analysis.