Packet fragmentation is a well-documented IDS evasion technique in CEH v13 Network and Perimeter Hacking. Attackers fragment packets to evade detection by overwhelming or confusing intrusion detection systems, especially those that rely on simple pattern matching.

CEH v13 explains that anomaly-based IDS systems are particularly effective against evasion techniques like packet fragmentation because they analyze deviations from normal network behavior, rather than relying on static signatures. Fragmented packets often create unusual traffic patterns, abnormal packet sizes, or irregular reassembly behavior, which anomaly-based systems are designed to detect.

Signature-based IDS solutions struggle against fragmentation because attackers can split malicious payloads across multiple packets in ways that bypass predefined signatures. Rejecting all fragmented packets (Option C) is impractical and could disrupt legitimate network communication, as fragmentation is a normal part of TCP/IP networking.

Recognizing regular intervals (Option A) is unreliable, as attackers can randomize packet timing. CEH v13 clearly recommends anomaly-based detection to counter advanced evasion techniques.

Thus, Option B is the most effective and CEH-aligned IDS configuration.