- A
2 VLAN attachments, 4 BGP sessions
Why wrong: 4 BGP sessions would be for 99.999% SLA, but question asks for 99.99%.
- B
2 VLAN attachments, 2 BGP sessions (one per attachment)
Two attachments on redundant links provide 99.99% availability.
- C
2 VLAN attachments, 1 BGP session
Why wrong: Each VLAN attachment needs its own BGP session for redundancy.
- D
1 VLAN attachment, 1 BGP session
Why wrong: Single attachment provides no redundancy.
Question 148 of 1,000
PCNE Practice Question: Designing, Planning, and Prototyping a GCP Network
This PCNE practice question tests your understanding of designing, planning, and prototyping a gcp network. 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.
An engineer is designing a hybrid network with a 10 Gbps Dedicated Interconnect. They require 99.99% availability for the connection. What is the minimum number of VLAN attachments and BGP sessions recommended?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"minimum / minimize"Why it matters: Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
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
✓
2 VLAN attachments, 2 BGP sessions (one per attachment)
To achieve 99.99% availability, you need at least 2 VLAN attachments (each on different physical links) and 2 BGP sessions. For higher SLAs, use 2 attachments and 4 BGP sessions.
Key principle: A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
2 VLAN attachments, 4 BGP sessions
Why it's wrong here
4 BGP sessions would be for 99.999% SLA, but question asks for 99.99%.
- ✓
2 VLAN attachments, 2 BGP sessions (one per attachment)
Why this is correct
Two attachments on redundant links provide 99.99% availability.
Clue confirmation
The clue word "minimum / minimize" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
- ✗
2 VLAN attachments, 1 BGP session
- ✗
1 VLAN attachment, 1 BGP session
Why it's wrong here
Single attachment provides no redundancy.
Common exam traps
Common exam trap: an active trunk can still block the VLAN you need
A trunk being up does not prove every VLAN is crossing it. Check allowed VLAN lists, native VLAN mismatch, VLAN existence and access-port assignment.
Detailed technical explanation
How to think about this question
VLAN questions usually combine access-port and trunking clues. The key is to identify whether the issue is local to one switchport, caused by the trunk, or caused by the VLAN not existing where it needs to exist.
KKey Concepts to Remember
- Access ports place end devices into a single VLAN.
- Trunk ports carry multiple VLANs between switches.
- Allowed VLAN lists decide which VLANs can cross a trunk.
- Native VLAN mismatch can create confusing symptoms.
TExam Day Tips
- Use show vlan brief to verify access VLANs.
- Use show interfaces trunk to verify trunk state and allowed VLANs.
- Do not treat every same-VLAN issue as a routing problem.
Key takeaway
A trunk being up does not mean the VLAN is allowed across it. Always verify the allowed VLAN list and whether the VLAN exists on both switches.
Real-world example
How this comes up in practice
An e-commerce site experiences heavy traffic on Black Friday and near-zero traffic during off-peak weeks. Rather than provisioning permanent large VMs, the team uses auto-scaling groups that add capacity automatically under load and reduce it overnight. Questions like this test whether you understand elasticity, availability zones, and cloud compute scaling patterns.
Visual reference
What to study next
Got this wrong? Here's your next step.
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related PCNE questions on switching, trunking, and access-port configuration.
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FAQ
Questions learners often ask
What does this PCNE question test?
Designing, Planning, and Prototyping a GCP Network — This question tests Designing, Planning, and Prototyping a GCP Network — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: 2 VLAN attachments, 2 BGP sessions (one per attachment) — To achieve 99.99% availability, you need at least 2 VLAN attachments (each on different physical links) and 2 BGP sessions. For higher SLAs, use 2 attachments and 4 BGP sessions.
What should I do if I get this PCNE question wrong?
Review VLAN allowed lists, native VLAN mismatch detection, and how to verify VLAN membership with show vlan brief and show interfaces trunk. Then practise related PCNE questions on switching, trunking, and access-port configuration.
Are there clue words in this question I should notice?
Yes — watch for: "minimum / minimize". Asks for the least resource use — fewest addresses, smallest subnet, lowest overhead. Eliminate over-provisioned options even if they would technically work.
What is the key concept behind this question?
Access ports place end devices into a single VLAN.
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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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