300-410 Layer 3 Technologies Practice Question
A network administrator is configuring OSPF on a Cisco router. The router is connected to two different OSPF areas: Area 0 and Area 1. The administrator wants to summarize routes from Area 1 into Area 0. Which command should be used on the Area Border Router (ABR) to accomplish this?
⚠ Common exam trap
A common mix-up: candidates confuse inter-area summarization with external summarization, leading to the use of 'summary-address' instead of 'area range'.
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
✓
area 1 range 10.1.0.0 255.255.0.0
Inter-area route summarization in OSPF is performed on ABRs using the 'area range' command. The area specified is the source area from which routes are summarized. In this case, routes from Area 1 are summarized before being advertised into Area 0. This reduces the number of LSAs and routing entries, improving scalability. The other commands either summarize external routes or apply to the wrong area, and thus do not meet the requirement.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
summary-address 10.1.0.0 255.255.0.0
Why it's wrong here
The 'summary-address' command is used on an Autonomous System Boundary Router (ASBR) to summarize external routes redistributed into OSPF. It creates a summary Type-5 LSA for external routes. In this scenario, the routes are internal to Area 1 and need to be summarized into Area 0, which is an inter-area summarization task, not external. Therefore, this command is not appropriate; it would not summarize internal Area 1 routes.
- ✗
ip summary-address ospf 1 10.1.0.0 255.255.0.0
Why it's wrong here
The 'ip summary-address ospf' command is used in interface configuration mode to summarize routes on a per-interface basis, typically for OSPFv3 or for specific scenarios like stub areas. It is not the standard method for inter-area summarization on an ABR in OSPFv2. The correct command for OSPFv2 inter-area summarization is 'area range', which is configured in router configuration mode. This command would not achieve the desired summarization from Area 1 into Area 0.
- ✓
area 1 range 10.1.0.0 255.255.0.0
Why this is correct
The 'area 1 range' command is used on an ABR to summarize inter-area routes from the specified area into other areas. It must be configured on the ABR, and the area specified is the source area (Area 1). This command aggregates routes from Area 1 into a single summary LSA that is advertised into Area 0. It is the correct method for inter-area route summarization in OSPF, reducing the size of the link-state database and routing tables in the backbone.
- ✗
area 0 range 10.1.0.0 255.255.0.0
Why it's wrong here
The 'area 0 range' command would summarize routes from Area 0 into other areas. However, the requirement is to summarize routes from Area 1 into Area 0. Configuring summarization on Area 0 would affect routes originating in the backbone, not those from Area 1. Since the ABR is the boundary between Area 0 and Area 1, the summarization must be applied to the source area (Area 1) to aggregate its routes before advertising them into Area 0.
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.
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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.