PCNE Configuring network services Practice Question
This PCNE practice question tests your understanding of configuring network services. 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.
An organization has a Dedicated Interconnect with Cloud Router configured for BGP. The on-premises network advertises a prefix that overlaps with an existing VPC subnet. How does Google Cloud handle the overlapping prefix?
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
It rejects the prefix and does not install a dynamic route for it.
When a Dedicated Interconnect with Cloud Router receives a BGP advertisement for a prefix that overlaps with an existing VPC subnet, Google Cloud rejects the prefix and does not install a dynamic route for it. This is because VPC subnet routes always take precedence over dynamically learned routes, and accepting an overlapping prefix would create ambiguity in forwarding decisions. The Cloud Router enforces this behavior to maintain the integrity of the VPC's internal addressing.
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.
✗
It accepts the prefix but static routes have higher priority.
Why it's wrong here
Overlapping prefixes are not accepted at all.
✗
It accepts the prefix and gives it higher priority than the VPC subnet.
Why it's wrong here
Overlapping prefixes are rejected, not accepted.
✓
It rejects the prefix and does not install a dynamic route for it.
Why this is correct
Google Cloud rejects overlapping prefixes to maintain routing integrity.
Related concept
Read the scenario before looking for a memorised answer.
✗
It accepts the prefix and load balances traffic between the two locations.
Why it's wrong here
Overlapping prefixes are rejected, not load-balanced.
Common exam traps
Common exam trap: answer the scenario, not the keyword
The trap here is that candidates often assume BGP routes can override VPC subnet routes due to the dynamic nature of BGP, but Google Cloud enforces a strict priority hierarchy where VPC subnet routes are always preferred over any dynamically learned or static route.
Detailed technical explanation
How to think about this question
Under the hood, Google Cloud uses a route priority system where VPC subnet routes have an implicit priority of 0, the highest possible. BGP-learned routes via Cloud Router have a default priority of 100, and static routes have a priority of 1000. When a BGP advertisement overlaps with a VPC subnet, the Cloud Router performs a prefix match and, finding a more specific or equal-length match with a higher-priority route, discards the BGP route to avoid ECMP or blackholing. This behavior is consistent with RFC 4271 and Google's custom routing architecture, ensuring that on-premises advertisements cannot override VPC internal addressing.
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 healthcare organisation deploys an application with a public-facing web tier and a private database tier. The database subnet has no public IP and only accepts connections from the web tier's security group. Questions like this test whether you can design cloud network isolation using VNets/VPCs, subnets, and security group rules.
What to study next
Got this wrong? Here's your next step.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
Configuring network services — This question tests Configuring network services — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: It rejects the prefix and does not install a dynamic route for it. — When a Dedicated Interconnect with Cloud Router receives a BGP advertisement for a prefix that overlaps with an existing VPC subnet, Google Cloud rejects the prefix and does not install a dynamic route for it. This is because VPC subnet routes always take precedence over dynamically learned routes, and accepting an overlapping prefix would create ambiguity in forwarding decisions. The Cloud Router enforces this behavior to maintain the integrity of the VPC's internal addressing.
What should I do if I get this PCNE 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.
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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.
Question Discussion
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