ISC Practice Question: Systems Security Implementation Verification And Validation
When validating a firewall's implementation, what does checking the 'Implicit Deny' rule verify?
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
That no traffic is allowed unless explicitly permitted.
The implicit deny rule is the final catch-all rule that drops all traffic not explicitly allowed.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
That the firewall is blocking all outgoing traffic.
Why it's wrong here
Implicit deny applies to both ingress and egress if the rules are written correctly, but its purpose is general traffic blocking.
- ✗
That the firewall can handle high traffic volumes.
Why it's wrong here
This relates to performance, not security policy enforcement.
- ✗
That the firewall is correctly logging denied packets.
Why it's wrong here
Logging is an auxiliary function; the rule itself acts as a gatekeeper.
- ✓
That no traffic is allowed unless explicitly permitted.
Why this is correct
This is the principle of least privilege in networking; verifying this rule confirms the default-deny posture.
About these practice questions
This ISC question is part of Courseiva's 209-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed August 2026 · checked against the official (ISC)² exam blueprint
This ISC practice question is part of Courseiva's free (ISC)² certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the ISC exam.