- A
The VLAN attachments are not configured with the same Cloud Router.
Why wrong: They should be connected to the same Cloud Router for active-active to work.
- B
The BGP timers are set too high, causing slow convergence.
Why wrong: Slow convergence would cause a temporary outage, not packet loss after failover.
- C
The on-premises router is not configured with equal-cost multipath (ECMP).
Why wrong: ECMP is needed for load balancing across both circuits, but lack of ECMP would not cause packet loss after failover; it would just not use both.
- D
The remaining circuit does not have sufficient bandwidth to handle the combined traffic load.
Active-active mode may use both circuits for load balancing; if one fails, all traffic goes to the other, potentially exceeding its capacity.
PCNE Implementing Hybrid Interconnectivity Practice Question
This PCNE practice question tests your understanding of implementing hybrid interconnectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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.
A company has two Dedicated Interconnect circuits in different metro areas to meet the 99.99% SLA. They have configured active-active mode. During a test, they intentionally bring down one circuit. They expect traffic to continue using the other circuit, but they notice packet loss during the failover. What could be the cause?
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 remaining circuit does not have sufficient bandwidth to handle the combined traffic load.
In active-active mode, both circuits are used simultaneously. When one fails, traffic is re-routed to the remaining one. If there is insufficient bandwidth on the remaining circuit, packet loss may occur due to congestion.
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.
- ✗
The VLAN attachments are not configured with the same Cloud Router.
Why it's wrong here
They should be connected to the same Cloud Router for active-active to work.
- ✗
The BGP timers are set too high, causing slow convergence.
Why it's wrong here
Slow convergence would cause a temporary outage, not packet loss after failover.
- ✗
The on-premises router is not configured with equal-cost multipath (ECMP).
Why it's wrong here
ECMP is needed for load balancing across both circuits, but lack of ECMP would not cause packet loss after failover; it would just not use both.
- ✓
The remaining circuit does not have sufficient bandwidth to handle the combined traffic load.
Why this is correct
Active-active mode may use both circuits for load balancing; if one fails, all traffic goes to the other, potentially exceeding its capacity.
Related concept
OSPF neighbours must agree on key parameters.
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.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
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 PCNE OSPF questions on adjacency and route selection.
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Implementing Hybrid Interconnectivity — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing Hybrid Interconnectivity — This question tests Implementing Hybrid Interconnectivity — OSPF neighbours must agree on key parameters..
What is the correct answer to this question?
The correct answer is: The remaining circuit does not have sufficient bandwidth to handle the combined traffic load. — In active-active mode, both circuits are used simultaneously. When one fails, traffic is re-routed to the remaining one. If there is insufficient bandwidth on the remaining circuit, packet loss may occur due to congestion.
What should I do if I get this PCNE 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 PCNE 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: Jul 4, 2026
This PCNE practice question is part of Courseiva's free Google Cloud 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 PCNE exam.
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