PCNE Configuring Network Services Practice Question
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?
⚠ Common exam trap
Many candidates 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.
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
✓
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.
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.
- ✗
It accepts the prefix and load balances traffic between the two locations.
Why it's wrong here
Overlapping prefixes are rejected, not load-balanced.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.