- A
The firewall has an ACL that denies traffic from 10.10.10.0/24. Update the ACL to allow this traffic.
PBR successfully forwards traffic to the firewall, but the firewall drops it due to an ACL. The routing is correct, but the firewall policy is blocking the traffic.
- B
The next-hop 192.168.1.1 is not reachable from R1 due to a routing issue.
Why wrong: The debug output shows packets being sent to 192.168.1.1, indicating the next-hop is reachable. The issue is on the firewall side.
- C
The route-map on R1 is missing a 'set ip next-hop verify-availability' command, causing it to forward traffic to an unreachable next-hop.
Why wrong: The next-hop is reachable, as evidenced by the debug output. The 'verify-availability' command would not help here because the firewall is reachable but drops the traffic.
- D
The VLAN interface on R1 has an ACL that is blocking traffic from 10.10.10.0/24.
Why wrong: If an ACL were blocking traffic on R1, the debug output would show packets being dropped before PBR. The debug shows packets being sent to the firewall, so no ACL is blocking on R1.
Quick Answer
The answer is that the firewall’s ACL is denying traffic from the source subnet 10.10.10.0/24, so you must update that ACL to permit the traffic. This is correct because Policy-Based Routing (PBR) on Router R1 successfully forwards packets to the firewall’s next-hop 192.168.1.1, as confirmed by debug ip policy, but the firewall itself then drops those packets due to its inbound ACL—a classic case of PBR traffic dropped by firewall ACL rather than a routing failure. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your ability to distinguish between a PBR forwarding issue and a firewall policy issue; a common trap is to troubleshoot the router’s routing table or PBR configuration when the real problem lies in the firewall’s access control. Remember the memory tip: “PBR gets it there, but ACL decides if it stays”—always verify the firewall’s ACL when traffic reaches the next-hop but gets no response.
300-410 Policy-Based Routing (PBR) Practice Question
This 300-410 practice question tests your understanding of policy-based routing (pbr). The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. After answering, compare your reasoning against the explanation and wrong-answer breakdown below. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
A network uses PBR to route traffic from a specific VLAN (10.10.10.0/24) through a firewall (next-hop 192.168.1.1). After a firewall policy change, traffic from this VLAN is being dropped. Router R1 shows: 'show ip policy' shows PBR applied, 'debug ip policy' shows traffic being forwarded to 192.168.1.1, but 'debug ip packet' on R1 shows packets being sent to 192.168.1.1 and no response. Router R2 (firewall) shows: 'show ip route 10.10.10.0' returns a route via 192.168.2.1, but 'show access-lists' on the firewall shows an ACL that denies traffic from 10.10.10.0/24. What is the root cause?
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
The firewall has an ACL that denies traffic from 10.10.10.0/24. Update the ACL to allow this traffic.
PBR forwards traffic to the firewall, but the firewall has an ACL that denies traffic from the source subnet (10.10.10.0/24). This is a policy issue on the firewall, not a routing issue. The solution is to update the firewall ACL to allow traffic from the source subnet.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
The firewall has an ACL that denies traffic from 10.10.10.0/24. Update the ACL to allow this traffic.
- ✗
The next-hop 192.168.1.1 is not reachable from R1 due to a routing issue.
Why it's wrong here
The debug output shows packets being sent to 192.168.1.1, indicating the next-hop is reachable. The issue is on the firewall side.
- ✗
The route-map on R1 is missing a 'set ip next-hop verify-availability' command, causing it to forward traffic to an unreachable next-hop.
Why it's wrong here
The next-hop is reachable, as evidenced by the debug output. The 'verify-availability' command would not help here because the firewall is reachable but drops the traffic.
- ✗
The VLAN interface on R1 has an ACL that is blocking traffic from 10.10.10.0/24.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Trap categories for this question
Command / output trap
The debug output shows packets being sent to 192.168.1.1, indicating the next-hop is reachable. The issue is on the firewall side.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
- Access ports place end devices into a single VLAN.
- Trunk ports carry multiple VLANs between switches.
- Allowed VLAN lists decide which VLANs can cross a trunk.
- Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
- Use show vlan brief to verify access VLANs.
- Use show interfaces trunk to verify trunk state and allowed VLANs.
- Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
A help-desk technician troubleshoots why a newly connected PC cannot reach shared printers on the same floor. The cable is good, the switch port is active, but the PC is in VLAN 20 and the printers are in VLAN 10. The uplink trunk only allows VLAN 10. A trunk being up does not mean every VLAN crosses it.
What to study next
Got this wrong? Here's your next step.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 300-410 questions on switching, trunking, and access-port configuration.
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FAQ
Questions learners often ask
What does this 300-410 question test?
Policy-Based Routing (PBR) — This question tests Policy-Based Routing (PBR) — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The firewall has an ACL that denies traffic from 10.10.10.0/24. Update the ACL to allow this traffic. — PBR forwards traffic to the firewall, but the firewall has an ACL that denies traffic from the source subnet (10.10.10.0/24). This is a policy issue on the firewall, not a routing issue. The solution is to update the firewall ACL to allow traffic from the source subnet.
What should I do if I get this 300-410 question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related 300-410 questions on switching, trunking, and access-port configuration.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Same concept, more angles
1 more ways this is tested on 300-410
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A network uses PBR to route traffic from a specific VLAN (10.10.10.0/24) through a firewall (next-hop 192.168.1.1). After a firewall replacement, traffic from this VLAN is being dropped. Router R1 shows: 'show route-map' shows the route-map is applied, 'show ip policy' shows the policy on the VLAN interface, but 'debug ip packet' shows packets being sent to 192.168.1.1 and no response. Router R2 (firewall) shows: 'show ip route 10.10.10.0' returns a route via 192.168.2.1, but the firewall is configured to drop traffic from 10.10.10.0/24. What is the root cause?
hard- ✓ A.The firewall is configured to drop traffic from the source subnet 10.10.10.0/24. Update the firewall policy to allow this traffic.
- B.The next-hop 192.168.1.1 is not reachable from R1 due to a routing issue.
- C.The route-map on R1 is missing a 'set ip next-hop verify-availability' command, causing it to forward traffic to an unreachable next-hop.
- D.The VLAN interface on R1 has an ACL that is blocking traffic from 10.10.10.0/24.
Why A: PBR forwards traffic to the firewall, but the firewall is configured to drop traffic from the source subnet (10.10.10.0/24). This is a policy issue on the firewall, not a routing issue. The solution is to update the firewall policy to allow traffic from the source subnet.
Last reviewed: Jun 18, 2026
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