According to the Certified Ethical Hacker (CEH) IDS/IPS and Evasion Techniques module, packet fragmentation is a technique attackers use to split malicious payloads into smaller fragments so that signature-based IDS sensors may fail to reassemble and inspect the complete packet.

CEH explains that anomaly-based IDS systems are more effective against fragmentation evasion because they analyze behavioral deviations rather than relying solely on known signatures. Fragmented traffic often deviates from baseline network behavior in terms of packet size, sequencing, and reassembly anomalies.

Option A is correct because anomaly-based detection can identify abnormal fragmentation behavior even if the payload itself does not match known signatures.

Option B is unreliable, as attackers do not use consistent intervals.

Option C is impractical, since legitimate traffic may be fragmented.

Option D is less effective because signature-based IDS systems can be bypassed by fragmentation techniques.

CEH recommends packet normalization and anomaly-based detection as effective countermeasures.