CCNA IP Routing Practice Question
Exhibit
R1# show ip route 172.16.0.0
Routing entry for 172.16.0.0/16
Known via "ospf 1", distance 110, metric 20, type inter area
Redistributing via ospf 1
Last update from 10.1.1.2 on GigabitEthernet0/0, 00:02:15 ago
Routing Descriptor Blocks:
* 10.1.1.2, from 10.2.2.2, 00:02:15 ago, via GigabitEthernet0/0
Route metric is 20, traffic share count is 1Refer to the exhibit. A network engineer is verifying OSPF routing on R1. All routers in the topology are expected to reside in OSPF area 0, and the network 172.16.0.0/16 should be advertised from R2 within the same area. The engineer issues the show ip route 172.16.0.0 command on R1 and sees the output in the exhibit. The engineer expected to see an intra-area route (O) instead of an inter-area route (O IA). What is the most likely cause of this discrepancy?
⚠ Common exam trap
Cisco often tests the distinction between intra-area and inter-area OSPF routes, and the trap here is that candidates mistakenly think a high metric or mismatched process ID can change the route type, when in fact only the area configuration determines whether a route is O or O IA.
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 destination network 172.16.0.0/16 is located in a different OSPF area.
The route 172.16.0.0/16 appears as O IA (inter-area) on R1, which means R1 learned it via a Type 3 LSA from an ABR. For the route to be intra-area (O), the destination network must reside in the same OSPF area (area 0) as R1. Since R2 is advertising this network, if it were truly in area 0, R1 would see an O route. The O IA designation indicates that the network is in a different area, likely because R2's interface connected to 172.16.0.0/16 is configured in a different OSPF area, or R2 is acting as an ABR.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
R1 has a mismatched OSPF process ID compared to the ABR.
Why it's wrong here
OSPF process IDs are locally significant and only identify the OSPF instance running on that router itself. There is no requirement for process IDs to match between neighboring routers for adjacency formation or route exchange, so a mismatch would neither prevent a route from being installed nor alter its classification as intra-area (Type-1) or inter-area (Type-3). The routing table entry showing 'inter area' is solely determined by the LSA type generated by the ABR, which depends on the destination network's area membership—not on the process ID.
- ✗
The network type on GigabitEthernet0/0 is configured as non-broadcast, preventing full adjacency.
Why it's wrong here
A non-broadcast network type could prevent neighbor formation, but the route is present in the routing table, indicating adjacency is established. Even if adjacency exists, the network type does not alter whether a route is intra-area or inter-area.
- ✗
The metric for the route is too high, causing OSPF to treat it as an inter-area route.
Why it's wrong here
OSPF classifies routes based on the LSA type (Type-1 for intra-area, Type-3 for inter-area), not on the metric value. A high metric would still result in an O route if the network is in the same area.
- ✓
The destination network 172.16.0.0/16 is located in a different OSPF area.
Why this is correct
The routing table entry shows 'type inter area'. This indicates the prefix is being learned via an OSPF Type-3 summary LSA, which is only generated when the network is in a different area than the local router. Therefore, the network is indeed in a different area, contradicting the assumption that R1 and the destination are both in area 0.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓The destination network 172.16.0.0/16 is located in a different OSPF area.Correct answer▾
Why this is correct
The routing table entry shows 'type inter area'. This indicates the prefix is being learned via an OSPF Type-3 summary LSA, which is only generated when the network is in a different area than the local router. Therefore, the network is indeed in a different area, contradicting the assumption that R1 and the destination are both in area 0.
✗R1 has a mismatched OSPF process ID compared to the ABR.Wrong answer — click to see why▾
Why this is wrong here
Candidates mistakenly assume that OSPF process IDs must match globally for proper LSA exchange, but they are only locally significant.
✗The network type on GigabitEthernet0/0 is configured as non-broadcast, preventing full adjacency.Wrong answer — click to see why▾
Why this is wrong here
Candidates may think that the network type influences the OSPF LSA type, but it only affects neighbor discovery and DR/BDR election, not the area origin of LSAs.
✗The metric for the route is too high, causing OSPF to treat it as an inter-area route.Wrong answer — click to see why▾
Why this is wrong here
Candidates sometimes confuse the metric influence with the route type, thinking that OSPF converts routes when the cost exceeds a threshold.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
OSPFv3 Single-Area Configuration for IPv6
Key term
ABR
An Area Border Router is an OSPF router that connects multiple OSPF areas, including the backbone area, and exchanges routing information between them.
Key term
LSA
A Link State Advertisement is a data packet used by OSPF routers to share information about their directly connected links and the state of those links with all other routers in the OSPF network.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.