The Certified Ethical Hacker (CEH) Incident Response lifecycle begins with Identification, followed by containment, eradication, recovery, and lessons learned. CEH documentation stresses that understanding the scope and nature of an incident is critical before taking disruptive action.

Option A is the correct initial response because it focuses on real-time monitoring and log analysis, which are essential during the identification phase. CEH materials emphasize analyzing logs, authentication failures, and traffic anomalies to confirm whether an incident has occurred and determine the attacker’s techniques, persistence level, and impact.

Option B, while valuable, is more appropriate after initial identification. Conducting deep outbound traffic audits without first understanding the attack vector can delay containment decisions.

Option C is premature. CEH warns that changing credentials too early may alert the attacker and cause them to escalate or destroy evidence.

Option D represents a containment strategy, not an initial response. CEH guidelines advise against immediately disconnecting systems unless there is confirmed active data exfiltration that cannot be otherwise controlled, as this may disrupt business operations and erase volatile forensic evidence.

Therefore, the CEH-approved approach is to monitor, analyze, and identify the incident before moving to containment and eradication.