- A
router ospf 1 area 0 range 10.0.0.0 255.255.252.0
This command creates a summary route for 10.0.0.0/22, which covers 10.0.1.0/24, 10.0.2.0/24, and 10.0.3.0/24. In OSPF, the 'area 0 range' command is used to summarize routes at an ABR, and the summary is advertised as a type 3 LSA to other areas, reducing the LSDB size.
- B
router ospf 1 summary-address 10.0.0.0 255.255.252.0
Why wrong: This is incorrect because 'summary-address' is used for EIGRP and BGP route summarization, not OSPF. In OSPF, the correct command is 'area range'.
- C
interface serial 0/0/0 ip summary-address ospf 1 10.0.0.0 255.255.252.0
Why wrong: This is incorrect because 'ip summary-address ospf' is used for OSPF summarization on an interface, but it is typically used for external routes (redistributed routes) or on an ASBR, not for summarizing internal area routes. The correct method for internal summarization is the 'area range' command.
- D
router ospf 1 area 0 range 10.0.0.0 255.255.255.0
Why wrong: This is incorrect because the mask 255.255.255.0 (/24) only summarizes the 10.0.0.0/24 subnet, which does not cover the three subnets (10.0.1.0/24, 10.0.2.0/24, 10.0.3.0/24). The correct mask should be 255.255.252.0 (/22) to include all three subnets.
Quick Answer
The answer is the `area 0 range 10.0.0.0 255.255.252.0` command configured under the OSPF process on R1. This is correct because OSPF route summarization using the `area range` command is performed on the Area Border Router (ABR)—in this case, R1—to condense multiple intra-area routes into a single Type 3 summary LSA before advertising them into another area, such as area 1. By specifying the summary address `10.0.0.0/22`, which covers the three /24 subnets, R1 reduces the link-state database size in area 1 and prevents route flapping from affecting the remote router. On the CCNA 200-301 v2 exam, this question tests your ability to distinguish between inter-area summarization (`area range`) and external route summarization (`summary-address`), a common trap where candidates mistakenly apply the command on the ASBR instead of the ABR. Remember the mnemonic: "ABR uses Area Range, ASBR uses Summary-Address."
CCNA IP Routing Practice Question
This 200-301 practice question tests your understanding of ip routing. This is a configuration task: choose the command set that satisfies every stated requirement. Small differences — like 'secret' vs 'password' or 'transport input ssh' vs 'all' — change whether the answer is correct. 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.
You are connected to R1 via console. R1 connects three subnets: 10.0.1.0/24 (area 0), 10.0.2.0/24 (area 0), and 10.0.3.0/24 (area 0). The serial link to R2 uses IP subnet 10.0.0.0/30 and is in OSPF area 1. The network administrator wants to advertise a single summary route for these three subnets to R2, reducing the OSPF link-state database size in area 1. R1 is already running OSPF with network statements for its connected subnets in their respective areas. You need to configure route summarization on R1 so that only the summary route is advertised to R2 via the serial link.
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
router ospf 1 area 0 range 10.0.0.0 255.255.252.0
The 'area 0 range' command creates a summary route for the specified range, which is then advertised as a type 3 summary LSA to other areas. This reduces routing table size and prevents flapping.
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.
- ✓
router ospf 1 area 0 range 10.0.0.0 255.255.252.0
Why this is correct
This command creates a summary route for 10.0.0.0/22, which covers 10.0.1.0/24, 10.0.2.0/24, and 10.0.3.0/24. In OSPF, the 'area 0 range' command is used to summarize routes at an ABR, and the summary is advertised as a type 3 LSA to other areas, reducing the LSDB size.
Related concept
OSPF neighbours must agree on key parameters.
- ✗
router ospf 1 summary-address 10.0.0.0 255.255.252.0
- ✗
interface serial 0/0/0 ip summary-address ospf 1 10.0.0.0 255.255.252.0
Why it's wrong here
This is incorrect because 'ip summary-address ospf' is used for OSPF summarization on an interface, but it is typically used for external routes (redistributed routes) or on an ASBR, not for summarizing internal area routes. The correct method for internal summarization is the 'area range' command.
- ✗
router ospf 1 area 0 range 10.0.0.0 255.255.255.0
Why it's wrong here
This is incorrect because the mask 255.255.255.0 (/24) only summarizes the 10.0.0.0/24 subnet, which does not cover the three subnets (10.0.1.0/24, 10.0.2.0/24, 10.0.3.0/24). The correct mask should be 255.255.252.0 (/22) to include all three subnets.
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.
✓router ospf 1 area 0 range 10.0.0.0 255.255.252.0Correct answer▾
Why this is correct
This command creates a summary route for 10.0.0.0/22, which covers 10.0.1.0/24, 10.0.2.0/24, and 10.0.3.0/24. In OSPF, the 'area 0 range' command is used to summarize routes at an ABR, and the summary is advertised as a type 3 LSA to other areas, reducing the LSDB size.
✗router ospf 1 summary-address 10.0.0.0 255.255.252.0Wrong answer — click to see why▾
Why this is wrong here
The 'summary-address' command is not valid for OSPF; it is used in EIGRP and BGP.
Why candidates choose this
Candidates may confuse OSPF summarization with EIGRP summarization, as both protocols use similar concepts but different commands.
✗interface serial 0/0/0 ip summary-address ospf 1 10.0.0.0 255.255.252.0Wrong answer — click to see why▾
Why this is wrong here
The 'ip summary-address ospf' command is used for external route summarization, not for summarizing internal OSPF routes within an area.
Why candidates choose this
Candidates might think that summarization is configured on the interface facing the upstream router, but OSPF internal summarization is done at the area level, not per interface.
✗router ospf 1 area 0 range 10.0.0.0 255.255.255.0Wrong answer — click to see why▾
Why this is wrong here
The mask 255.255.255.0 is too specific and only covers a single /24 network, not the required range.
Why candidates choose this
Candidates may mistakenly use a /24 mask thinking it summarizes the subnets, but they need to calculate the correct prefix length that covers all subnets.
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?”
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
This is incorrect because 'summary-address' is used for EIGRP and BGP route summarization, not OSPF. In OSPF, the correct command is 'area range'.
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.
What to study next
Got this wrong? Here's your next step.
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 200-301 OSPF questions on adjacency and route selection.
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FAQ
Questions learners often ask
What does this 200-301 question test?
IP Routing — This question tests IP Routing — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: router ospf 1 area 0 range 10.0.0.0 255.255.252.0 — The 'area 0 range' command creates a summary route for the specified range, which is then advertised as a type 3 summary LSA to other areas. This reduces routing table size and prevents flapping.
What should I do if I get this 200-301 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 200-301 OSPF questions on adjacency and route selection.
What is the key concept behind this question?
OSPF neighbours must agree on key parameters.
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Last reviewed: Jun 7, 2026
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.
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