This document discusses and analyzes different approaches to intrusion detection systems (IDS), including genetic algorithm approaches, data mining approaches, and intrusion detection in mobile ad hoc networks (MANETs). It provides an overview of genetic algorithm based IDS and data mining techniques for IDS. It also proposes a hybrid approach that combines anomaly detection and signature-based IDS to detect both known and unknown attacks. The document concludes that a critical analysis of various IDS techniques was performed and a hybrid approach is promising for intrusion detection in MANETs.