350-401 Security Practice Question
A network engineer is configuring a Zone-Based Firewall on a Cisco IOS XE router. The design requires that traffic from the inside zone to the outside zone be inspected, that return traffic be permitted, and that traffic from the outside zone to the inside zone be dropped unless it matches an existing session. Which configuration element is required to achieve this behavior?
⚠ Common exam trap
The trap here is thinking that a drop policy on the outside-to-inside zone pair is needed, when in ZBF the inspect action on the reverse direction handles return traffic automatically.
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
✓
A zone pair with a service policy that applies inspect to inside-to-outside traffic
Zone-Based Firewall policies are applied to zone pairs and are directional. Inspecting traffic from the inside zone to the outside zone creates session state, which allows return traffic from outside to inside automatically. Without the inspect action on that zone pair, the default inter-zone deny would block return traffic, so the inspect policy is the essential element.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
A class map that matches on the outside interface and an ACL that permits established sessions
Why it's wrong here
Class maps and ACLs are used within policy maps, but an ACL that permits established sessions is a reflexive ACL approach, not ZBF. ZBF does not rely on established keywords in ACLs; it uses the inspect action to create state entries. Configuring an established ACL would not integrate with the zone pair model and would not provide the stateful inspection required.
- ✓
A zone pair with a service policy that applies inspect to inside-to-outside traffic
Why this is correct
Zone-Based Firewall uses zone pairs to define directional policy between zones. Applying a service policy with the inspect action on the inside-to-outside zone pair creates stateful inspection, so return traffic from the outside zone is automatically permitted. Without this inspect action, the router treats the zones as separate and return traffic would be dropped by the default inter-zone deny.
- ✗
A policy map with the pass action applied to the outside-to-inside zone pair
Why it's wrong here
The pass action allows traffic without inspection or state tracking, which would permit outside-to-inside traffic unconditionally, violating the requirement. The scenario specifically requires that outside-to-inside traffic be dropped unless it matches an existing session. The pass action does not create session state, so it cannot satisfy that requirement.
- ✗
A zone pair with a service policy that applies drop to the outside-to-inside zone pair
Why it's wrong here
Applying drop to the outside-to-inside zone pair would block all traffic in that direction, including return traffic for sessions initiated from inside, because ZBF return traffic is permitted only when the inspect action creates a state entry. Without an inspect policy on the inside-to-outside zone pair, no sessions exist and all return traffic is dropped, breaking connectivity.
Visual reference
Go deeper
Related to this question
About these practice questions
One of 1,923 original 350-401 practice questions on Courseiva, each with a full explanation and wrong-answer analysis — not exam dumps or protected exam content. 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 September 2026 · checked against the official Cisco exam blueprint
This 350-401 practice question is part of Courseiva's free Cisco 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 350-401 exam.