Which method is primarily used by an IDS to detect intrusions?

An Intrusion Detection System (IDS) primarily relies on two fundamental methods for detecting intrusions: signature analysis and anomaly analysis.

Signature analysis involves comparing network traffic against a database of known attack patterns or signatures. When the IDS detects a pattern that matches a known signature, it can identify the specific type of intrusion, allowing for quick response measures. This method is effective for known threats but may struggle with new or unknown attack patterns, which is where anomaly analysis comes into play.

Anomaly analysis, on the other hand, focuses on identifying deviations from established baselines of normal network behavior. This method looks for outliers or unusual activity that could indicate a potential threat, regardless of whether it matches a known signature. It is particularly useful in detecting zero-day attacks or other novel intrusion attempts that the signature-based approach may not catch.

Together, these methods allow an IDS to provide comprehensive monitoring and detection capabilities, ensuring that it can respond to both known and unknown threats effectively.