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300-410 Practice Question: Is troubleshooting PBR on a Cisco router where…
A network engineer is troubleshooting PBR on a Cisco router where traffic from VLAN 100 (192.168.10.0/24) should be forwarded to next-hop 10.10.10.2 via a route map named 'VLAN100-PBR'. The engineer has applied the route map to interface GigabitEthernet0/0.100 (subinterface) using 'ip policy route-map VLAN100-PBR'. The engineer verifies that the route map is correctly configured with 'match ip address 100' and 'set ip next-hop 10.10.10.2', and the access list 100 matches the source subnet. However, traffic from VLAN 100 is still forwarded using the routing table. What is the most likely cause?
⚠ Common exam trap
300-410 often tests the assumption that applying PBR to a subinterface automatically covers all traffic from that VLAN — candidates overlook that PBR matches on the actual ingress interface, not the logical VLAN.
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 traffic is arriving on the physical interface GigabitEthernet0/0 instead of the subinterface GigabitEthernet0/0.100.
PBR is applied on the interface where traffic enters the router. If VLAN 100 traffic is arriving on the physical interface GigabitEthernet0/0 (for example, because the subinterface is not properly configured for 802.1Q encapsulation or the switch is sending untagged frames), the policy applied to GigabitEthernet0/0.100 will never be evaluated. The route map is correct, so the most likely cause is that the ingress interface does not match where the policy is attached.
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 traffic is arriving on the physical interface GigabitEthernet0/0 instead of the subinterface GigabitEthernet0/0.100.
Why this is correct
PBR applies only to traffic entering the interface where the policy is attached. If VLAN 100 traffic is routed via the physical GigabitEthernet0/0 rather than the subinterface, the route map never triggers, so packets fall through to the routing table.
- ✗
The access list 100 is missing the 'permit' keyword; PBR only processes permit statements.
Why it's wrong here
Incorrect because access lists default to deny, but if the ACL is missing 'permit', no traffic would match; however, the symptom is that traffic is forwarded normally (routing table), not dropped, indicating the ACL is likely correct.
- ✗
The 'set ip next-hop' command must be followed by 'force' to override the routing table.
Why it's wrong here
The 'force' keyword only bypasses the default next-hop check when the specified next-hop is unreachable; it does not override an already-working routing table lookup. It is tempting because 'force' sounds like an override, but the actual fault is that PBR is applied inbound on the subinterface, so locally generated or misdirected traffic never matches the policy.
- ✗
The route map must be applied to the VLAN interface (SVI) instead of the subinterface.
Why it's wrong here
Applying the route map to the SVI would not fix this, because policy routing on the subinterface already matches ingress traffic from VLAN 100. It is tempting since SVIs represent VLANs logically, but the real cause is that the policy must be applied with 'ip policy route-map' in the correct direction on the interface receiving the traffic.
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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 300-410 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 300-410 exam.