- A
The VLAN attachment is configured with a lower bandwidth cap
VLAN attachments have a configurable bandwidth limit (e.g., 500 Mbps, 1 Gbps). If set lower than the physical link, throughput will be capped.
- B
Cloud Router is not using the partner's ASN
Why wrong: The ASN does not affect throughput.
- C
The VPC MTU is set to 1500 bytes
Why wrong: MTU influences packet size but not aggregate throughput to this extent.
- D
The on-premises router does not support BGP multipath
Why wrong: While multipath helps, it is not the primary cause for a single VLAN attachment.
Question 865 of 982
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. 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.
A company is using Partner Interconnect with a 2 Gbps VLAN attachment. They notice that throughput is only about 500 Mbps during peak hours. They have verified that the on-premises link is not saturated. What is the most likely cause?
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"most likely"Why it matters: Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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 VLAN attachment is configured with a lower bandwidth cap
Partner Interconnect VLAN attachments have a maximum throughput that depends on the partner's capability. If the throughput is lower than expected, it may be due to the partner limiting the bandwidth or the VLAN attachment configuration. However, a common cause is that the BGP session's route advertisement or Cloud Router configuration is not using multiple paths. Another possibility: the traffic is not using the VLAN attachment because of routing preferences. But given the scenario, the most plausible cause is that the VLAN attachment is configured with a lower bandwidth limit than the physical link.
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.
- ✓
The VLAN attachment is configured with a lower bandwidth cap
Why this is correct
VLAN attachments have a configurable bandwidth limit (e.g., 500 Mbps, 1 Gbps). If set lower than the physical link, throughput will be capped.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Access ports place end devices into a single VLAN.
- ✗
Cloud Router is not using the partner's ASN
Why it's wrong here
The ASN does not affect throughput.
- ✗
The VPC MTU is set to 1500 bytes
Why it's wrong here
MTU influences packet size but not aggregate throughput to this extent.
- ✗
The on-premises router does not support BGP multipath
Why it's wrong here
While multipath helps, it is not the primary cause for a single VLAN attachment.
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
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.
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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Designing, Planning, and Prototyping a GCP Network — study guide chapter
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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: The VLAN attachment is configured with a lower bandwidth cap — Partner Interconnect VLAN attachments have a maximum throughput that depends on the partner's capability. If the throughput is lower than expected, it may be due to the partner limiting the bandwidth or the VLAN attachment configuration. However, a common cause is that the BGP session's route advertisement or Cloud Router configuration is not using multiple paths. Another possibility: the traffic is not using the VLAN attachment because of routing preferences. But given the scenario, the most plausible cause is that the VLAN attachment is configured with a lower bandwidth limit than the physical link.
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: "most likely". Probability qualifier — the question wants the most probable cause or outcome, not a guaranteed one. Eliminate low-probability options.
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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