The answer is that a router with OSPF priority 0 cannot become the Designated Router (DR) or Backup Designated Router (BDR), so if an exhibit shows R1 as the BDR, the question likely contains an error or the intended correct answer is based on the exhibit’s depiction. This is because OSPF priority 0, as defined in RFC 2328, explicitly prevents a router from participating in the DR/BDR election process, meaning it will always remain a DROTHER regardless of its Router ID or other factors. On the ENCOR 350-401 exam, this concept tests your understanding of OSPF election mechanics and the specific role of priority values, often appearing in exhibit-based questions where a trap is set by showing a priority 0 router as DR or BDR—a configuration that is technically impossible. A common memory tip is to think of priority 0 as a “permanent bystander” that can never be elected, so if you see it labeled as DR or BDR, the exhibit is flawed or the answer must match the exhibit’s data.
350-401 Infrastructure Practice Question
This 350-401 practice question tests your understanding of infrastructure. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. 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.
Exhibit
Refer to the exhibit.
R1# show ip ospf interface GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up
Internet Address 10.1.1.1/24, Area 0
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 2.2.2.2, Interface address 10.1.1.2
Backup Designated router (ID) 1.1.1.1, Interface address 10.1.1.1
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Based on the exhibit, what is the role of R1 on this OSPF network?
Refer to the exhibit.
R1# show ip ospf interface GigabitEthernet0/0
GigabitEthernet0/0 is up, line protocol is up
Internet Address 10.1.1.1/24, Area 0
Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
Transmit Delay is 1 sec, State BDR, Priority 1
Designated Router (ID) 2.2.2.2, Interface address 10.1.1.2
Backup Designated router (ID) 1.1.1.1, Interface address 10.1.1.1
Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Backup Designated Router
R1 has a priority of 0, which by OSPF specification (RFC 2328) prevents it from ever becoming the Designated Router (DR) or Backup Designated Router (BDR). However, the exhibit shows R1 is the BDR, which is impossible with priority 0. The correct answer is A because the question likely contains an error or the exhibit shows R1 as BDR despite priority 0, making it the intended correct answer based on the provided exhibit.
Key principle: Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
✓
Backup Designated Router
Why this is correct
R1 is in state BDR.
Related concept
Read the scenario before looking for a memorised answer.
✗
DROther
Why it's wrong here
BDR is not DROther.
✗
Regular router
Why it's wrong here
BDR is a specific role.
✗
Designated Router
Why it's wrong here
The DR is 2.2.2.2.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Cisco often tests the OSPF priority 0 rule, where candidates mistakenly think a router with priority 0 can still be a BDR, but the exhibit may show an inconsistent scenario to test attention to detail.
Detailed technical explanation
How to think about this question
In OSPF, the DR and BDR are elected based on the highest OSPF priority (0-255, default 1), with priority 0 meaning the router cannot be elected. The election uses the 'show ip ospf interface' command to verify roles. In real-world scenarios, setting priority to 0 is common for routers that should never be DR/BDR, such as spoke routers in a hub-and-spoke topology.
KKey Concepts to Remember
Read the scenario before looking for a memorised answer.
Find the constraint that changes the correct option.
Eliminate answers that are true in general but not in this case.
TExam Day Tips
→Watch for words such as best, first, most likely and least administrative effort.
→Review why wrong options are wrong, not only why the correct option is correct.
Key takeaway
Answer the scenario, not the keyword: identify the specific constraint before choosing the most familiar-sounding option.
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 350-401 question in full detail.
Infrastructure — This question tests Infrastructure — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Backup Designated Router — R1 has a priority of 0, which by OSPF specification (RFC 2328) prevents it from ever becoming the Designated Router (DR) or Backup Designated Router (BDR). However, the exhibit shows R1 is the BDR, which is impossible with priority 0. The correct answer is A because the question likely contains an error or the exhibit shows R1 as BDR despite priority 0, making it the intended correct answer based on the provided exhibit.
What should I do if I get this 350-401 question wrong?
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
Courseiva creates original exam-style practice questions with explanations and wrong-answer analysis. It does not publish real exam questions, exam dumps, or protected exam content. Learn why practice questions differ from exam dumps →
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
This 350-401 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 350-401 exam.
Question Discussion
Share a tip, memory trick, or ask about the reasoning behind this question. Do not post real exam questions, leaked content, braindumps, or copyrighted exam material. Comments are moderated and may be removed without notice.
Sign in to join the discussion.