CCNA IP Routing Practice Question
Exhibit
Current state: R1 priority 1 - DR R2 priority 1 - BDR R3 priority changed from 1 to 200 after adjacency formed
On a broadcast multiaccess segment, R3 has an OSPF priority of 255, but it is in the DROTHER state. Which explanation best fits OSPF behavior?
⚠ Common exam trap
A common exam trap is assuming that increasing a router's OSPF priority after the DR election will cause it to immediately become the new DR. Many candidates mistakenly believe OSPF DR election is preemptive and that the router with the highest priority always becomes DR instantly. However, OSPF DR election on broadcast networks is nonpreemptive, meaning the current DR remains until it fails or OSPF adjacency resets. This misunderstanding can lead to incorrect answers about why a router with a higher priority remains DROTHER, as in the case of R3 in the question.
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
✓
DR election is nonpreemptive on broadcast networks
On broadcast networks, OSPF DR and BDR election is not preemptive. If a DR is already elected, giving another router a higher priority later does not force a new election unless the current DR goes down or OSPF is reset on the segment.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
DR election is nonpreemptive on broadcast networks
Why this is correct
DR/BDR election is nonpreemptive on broadcast multiaccess networks: once the DR and BDR are elected, they remain in those roles until they fail or the OSPF process/interface is reset. Increasing a router's OSPF priority after the election (as with R3) does not force a new election, so the existing DR stays active even if R3 now has a higher priority. To replace the DR, you must clear the OSPF process or reload the router, not just adjust priority.
- ✗
A router cannot become DR if it uses a loopback router ID
Why it's wrong here
A loopback-derived router ID does not disqualify a router from becoming DR. OSPF router IDs are often assigned from a loopback address for stability, and the DR election uses OSPF priority first, then the highest router ID only as a tiebreaker. Using a loopback address as the router ID is a normal and recommended practice, and it certainly does not prevent R3 from being elected DR.
When this WOULD be correct
In a scenario where the question specifies that OSPF is configured to use loopback interfaces exclusively for router IDs and that the DR election process is limited to routers with physical interfaces only, this option would be correct, as it would imply that a router using a loopback ID cannot become DR.
- ✗
OSPF priority works only on point-to-point links
Why it's wrong here
OSPF priority is not limited to point-to-point links; it is specifically meaningful on broadcast and NBMA segments, where a DR/BDR is elected using the highest priority value. Point-to-point links do not use DR/BDR election at all, so priority is irrelevant there. Since the exhibit shows a broadcast multiaccess segment, R3's priority is exactly the parameter that should be considered in the election.
When this WOULD be correct
If the question specified a scenario where OSPF priority settings were only applicable to point-to-point links and did not mention broadcast networks, then this option could be correct. For example, a question could ask about OSPF behavior in a purely point-to-point topology, where priority settings determine the DR election.
- ✗
R3's priority is lower than the current DR's priority
Why it's wrong here
The router's priority is compared only during the initial election process on that segment; after the existing DR is elected, a later higher priority does not trigger a new election. Furthermore, factors such as the area ID have no effect on DR selection on a broadcast segment—DR/BDR are chosen per segment by highest priority, not by area. Therefore claiming R3's priority is lower misidentifies the cause; even with equal or higher priority, the incumbent DR would remain due to nonpreemption.
When this WOULD be correct
In a different question setup where the scenario specifies that only routers in area 1 can participate in DR elections, this option would be correct. For example, if the question stated that R3 is in area 0 while other routers are in area 1, it would not be eligible to become DR.
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.
✓DR election is nonpreemptive on broadcast networksCorrect answer▾
Why this is correct
DR/BDR election is nonpreemptive on broadcast multiaccess networks: once the DR and BDR are elected, they remain in those roles until they fail or the OSPF process/interface is reset. Increasing a router's OSPF priority after the election (as with R3) does not force a new election, so the existing DR stays active even if R3 now has a higher priority. To replace the DR, you must clear the OSPF process or reload the router, not just adjust priority.
✗A router cannot become DR if it uses a loopback router IDWrong answer — click to see why▾
Why this is wrong here
This option is incorrect because OSPF allows routers to use loopback interfaces as router IDs, and a router can still become the DR regardless of the router ID type, as long as it has the highest priority or is the first to declare itself.
★ When this WOULD be the correct answer
In a scenario where the question specifies that OSPF is configured to use loopback interfaces exclusively for router IDs and that the DR election process is limited to routers with physical interfaces only, this option would be correct, as it would imply that a router using a loopback ID cannot become DR.
Why candidates choose this
Candidates may find this option tempting because they might confuse the role of router IDs with OSPF DR election, leading them to believe that the type of router ID could impact the ability to become DR.
✗OSPF priority works only on point-to-point linksWrong answer — click to see why▾
Why this is wrong here
OSPF priority can be configured on both broadcast and point-to-point links, and it is not limited to point-to-point links only. Therefore, the statement that OSPF priority works only on point-to-point links is incorrect in the context of broadcast networks.
★ When this WOULD be the correct answer
If the question specified a scenario where OSPF priority settings were only applicable to point-to-point links and did not mention broadcast networks, then this option could be correct. For example, a question could ask about OSPF behavior in a purely point-to-point topology, where priority settings determine the DR election.
Why candidates choose this
Candidates may be misled by the specific mention of OSPF priority, thinking it is a unique characteristic of point-to-point links, leading them to overlook its applicability in broadcast environments.
✗R3's priority is lower than the current DR's priorityWrong answer — click to see why▾
Why this is wrong here
This distractor assumes the election is based on current priority values, but OSPF DR election is nonpreemptive; even if R3's priority is higher, it will not become DR unless the current DR fails.
★ When this WOULD be the correct answer
In a different question setup where the scenario specifies that only routers in area 1 can participate in DR elections, this option would be correct. For example, if the question stated that R3 is in area 0 while other routers are in area 1, it would not be eligible to become DR.
Why candidates choose this
Candidates might choose this option due to a misunderstanding of OSPF area functions and their impact on router roles, leading them to believe that area membership directly affects DR election eligibility.
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
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Key term
Segment
A segment is a division of a larger network, such as a collision domain, broadcast domain, or a portion of a TCP data stream, used to organize traffic and improve performance.
Key term
OSPF
OSPF is a link-state routing protocol used to find the best path for data packets to travel across IP networks, like a smart GPS that recalculates routes when traffic changes.
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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.