The answer is that the access list 110 is not matching any traffic arriving on GigabitEthernet0/0, which is the most likely reason for the PBR zero matches. Policy-based routing relies on a route map to match specific traffic via an access list, and if no inbound packets satisfy the ACL’s conditions—here, TCP traffic from the 10.0.0.0/8 source to any destination on ports 80 or 443—the match counter remains at zero, even if the next-hop is reachable. On the Cisco CCNP ENARSI 300-410 exam, this scenario tests your ability to isolate whether the issue is a misconfigured match clause versus an unreachable next-hop, a common trap where candidates mistakenly blame routing when the ACL simply doesn’t see qualifying traffic. The key is to verify the ACL’s source, destination, and protocol against actual traffic flows on the applied interface. Remember the memory tip: “Zero matches? Check the catches”—meaning always inspect the ACL entries before assuming a routing problem.
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 engineer runs the following command on Router R1:
R1# show ip policy
Interface Route-map
GigabitEthernet0/0 PBR-TEST
R1# show route-map PBR-TEST
route-map PBR-TEST, permit, sequence 10
Match clauses:
ip address (access-lists): 110
Set clauses:
ip next-hop 192.168.100.1
Policy routing matches: 0 packets, 0 bytes
R1# show access-lists 110
Extended IP access list 110
10 permit tcp 10.0.0.0 0.255.255.255 any eq 80
20 permit tcp 10.0.0.0 0.255.255.255 any eq 443
R1# show ip route 192.168.100.1
Routing entry for 192.168.100.1/32
Known via "ospf 1", distance 110, metric 20
Last update from 10.1.1.2 on GigabitEthernet0/1
Based on this output, what is the most likely reason for zero policy routing matches?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue: "most likely"
Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The access list 110 is not matching any traffic arriving on GigabitEthernet0/0.
The access list 110 matches TCP traffic from 10.0.0.0/8 to any destination on ports 80 and 443. The route map is applied to GigabitEthernet0/0, but traffic arriving on that interface may not match these conditions. The next-hop is reachable, so the issue is likely that no traffic matching ACL 110 is entering GigabitEthernet0/0.
Key principle: OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
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 next-hop 192.168.100.1 is not reachable.
Why it's wrong here
The show ip route output shows it is reachable via OSPF.
✓
The access list 110 is not matching any traffic arriving on GigabitEthernet0/0.
Why this is correct
Zero matches indicate that no packets matching the ACL have been received on the interface where PBR is applied.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Sequence numbers do not affect matching; they just determine order.
✗
The route map needs to be applied globally.
Why it's wrong here
PBR is applied per interface; global application is not standard.
Common exam traps
Common exam trap: OSPF can fail even when IP connectivity looks correct
OSPF neighbour formation depends on matching areas, timers, network type, authentication and passive-interface behaviour. Do not choose an answer only because the devices can ping.
Trap categories for this question
Command / output trap
The show ip route output shows it is reachable via OSPF.
Detailed technical explanation
How to think about this question
OSPF questions usually test the details that control adjacency and route selection. Read the neighbour state, area, router ID and interface configuration before deciding what is wrong.
KKey Concepts to Remember
OSPF neighbours must agree on key parameters.
Router ID selection can affect neighbour relationships and LSDB output.
OSPF cost influences the preferred path.
A route can appear in OSPF information but not become the installed route.
TExam Day Tips
→Check area mismatch first when OSPF adjacency fails.
→Review passive interfaces when a network is advertised but no neighbour forms.
→Use show ip ospf neighbor and show ip route clues carefully.
Key takeaway
OSPF neighbour adjacency depends on matching area, hello/dead timers, network type, and authentication — IP reachability alone is not enough.
Real-world example
How this comes up in practice
A network engineer at a university connects two campus buildings via a fibre link. Both routers run OSPF, but no adjacency forms — even though both routers can ping each other. The engineer finds one router is in area 0 and the other in area 1. OSPF adjacency requires matching area numbers, hello/dead timers, and network type. IP reachability alone is not enough.
Related glossary terms
Concepts from this question explained
These glossary pages explain the core terms tested in this 300-410 question in full detail.
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 300-410 OSPF questions on adjacency and route selection.
Policy-Based Routing (PBR) — This question tests Policy-Based Routing (PBR) — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The access list 110 is not matching any traffic arriving on GigabitEthernet0/0. — The access list 110 matches TCP traffic from 10.0.0.0/8 to any destination on ports 80 and 443. The route map is applied to GigabitEthernet0/0, but traffic arriving on that interface may not match these conditions. The next-hop is reachable, so the issue is likely that no traffic matching ACL 110 is entering GigabitEthernet0/0.
What should I do if I get this 300-410 question wrong?
Review OSPF neighbour requirements — matching area type, hello and dead timers, network type, stub flags, and authentication. Study show ip ospf neighbor states (INIT, 2-WAY, FULL). Then practise related 300-410 OSPF questions on adjacency and route selection.
Are there clue words in this question I should notice?
Yes — watch for: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
About these practice questions
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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 engineer is troubleshooting PBR on a Cisco router where traffic from subnet 10.1.1.0/24 should be forwarded to next-hop 192.168.1.2. The route map 'PBR-10' is configured with 'match ip address 150' and 'set ip next-hop 192.168.1.2'. The engineer applies the route map to interface GigabitEthernet0/0. The engineer notices that PBR is not working, and the router is using the routing table to forward traffic. The engineer checks the ACL 150 and confirms it matches 10.1.1.0/24. The engineer also checks the interface configuration and sees 'ip policy route-map PBR-10' applied. What is the most likely cause?
medium
✓ A.The ACL 150 does not exist or is misconfigured, causing the route map to not match any traffic.
B.The 'set ip next-hop' command is misspelled as 'set ip nexthop'.
C.The router is running an older IOS version that does not support PBR.
D.The 'ip policy route-map' command is applied to the outgoing interface instead of the incoming interface.
Why A: If PBR is not working and the router uses the routing table, it could be because the route map is not being processed due to a missing 'match' statement or the route map being empty. However, a common cause is that the route map has a 'match ip address' that references an ACL that does not exist or is misconfigured. The engineer should verify that the ACL 150 exists and is correctly configured.
Variation 2. A network engineer runs the following command on Router R1:
R1# show ip policy
Interface Route-map
GigabitEthernet0/0 PBR-DEFAULT
R1# show route-map PBR-DEFAULT
route-map PBR-DEFAULT, permit, sequence 10
Match clauses:
ip address (access-lists): 150
Set clauses:
ip next-hop 10.0.0.2
Policy routing matches: 0 packets, 0 bytes
route-map PBR-DEFAULT, deny, sequence 20
Match clauses:
Set clauses:
Policy routing matches: 0 packets, 0 bytes
R1# show access-lists 150
Extended IP access list 150
10 permit ip 192.168.1.0 0.0.0.255 any
R1# show ip route 10.0.0.2
Routing entry for 10.0.0.2/32
Known via "ospf 1", distance 110, metric 20
Last update from 10.1.1.2 on GigabitEthernet0/1
Based on this output, what is the most likely problem?
medium
A.The deny sequence 20 is blocking all traffic from being policy-routed.
✓ B.No traffic matching ACL 150 is arriving on GigabitEthernet0/0.
C.The next-hop 10.0.0.2 is unreachable.
D.The route map is missing a permit statement.
Why B: The route map has a deny sequence 20 with no match clause, which means it matches all packets. Since route maps are processed in order, if sequence 10 does not match (zero matches), sequence 20 will match all remaining packets and deny them (i.e., not apply PBR), causing them to be routed normally. However, the counters show zero for both sequences, indicating no traffic is being processed at all, likely because no traffic matching ACL 150 arrives on the interface.
Variation 3. A network engineer runs the following command on Router R1:
R1# show route-map
route-map PBR-ROUTE, permit, sequence 10
Match clauses:
ip address (access-lists): ACL-PBR
Set clauses:
ip next-hop 192.168.1.2
Policy routing matches: 0 packets, 0 bytes
route-map PBR-ROUTE, permit, sequence 20
Match clauses:
Set clauses:
ip next-hop 192.168.2.2
Policy routing matches: 0 packets, 0 bytes
R1# show ip policy
Interface Route-map
GigabitEthernet0/0 PBR-ROUTE
Based on this output, what is the most likely problem?
medium
A.The route map is not applied to an interface.
✓ B.The access list ACL-PBR does not exist or matches no traffic.
C.The next-hop 192.168.1.2 is unreachable.
D.The route map is missing a permit statement.
Why B: The show route-map output shows zero policy routing matches. The route map is applied to the interface, but the access list ACL-PBR may not match any traffic, or traffic is not arriving on GigabitEthernet0/0. The set clause in sequence 20 is applied unconditionally (no match clause), which would normally match all traffic, but sequence 10 must be evaluated first; if ACL-PBR matches nothing, sequence 20 would match all, yet counters still show zero, indicating no traffic is being policy-routed at all.
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