- A
The Cloud Router BGP IP address is not in the same subnet as the VLAN attachment
The BGP IP addresses on Cloud Router and on-premises must be in the same /29 subnet assigned by the VLAN attachment.
- B
The VLAN attachment type should be PARTNER_PROVIDER
Why wrong: PARTNER_PROVIDER is for Layer 3 where provider manages BGP. Since they want to manage BGP themselves, PARTNER is correct.
- C
The IAM permissions for the Cloud Router are missing
Why wrong: IAM permissions affect API calls, not BGP session establishment.
- D
The on-premises router is using a different BGP AS number than configured
Why wrong: Different AS numbers would still allow BGP session establishment (eBGP). The session would come up but might affect route advertisement.
Question 686 of 982
PCNE Implementing Hybrid Interconnectivity Practice Question
This PCNE practice question tests your understanding of implementing hybrid interconnectivity. 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 has a Partner Interconnect connection (Layer 2) with a service provider. They need to configure BGP sessions on their on-premises router and Google Cloud Router. The engineer creates a VLAN attachment of type PARTNER. However, the BGP session does not come up. What is the most likely reason?
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 Cloud Router BGP IP address is not in the same subnet as the VLAN attachment
In Layer 2 Partner Interconnect, the customer must configure BGP sessions. The VLAN attachment type PARTNER requires the customer to manage BGP. Common issues include incorrect VLAN ID or IP addresses.
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 Cloud Router BGP IP address is not in the same subnet as the VLAN attachment
- ✗
The VLAN attachment type should be PARTNER_PROVIDER
Why it's wrong here
PARTNER_PROVIDER is for Layer 3 where provider manages BGP. Since they want to manage BGP themselves, PARTNER is correct.
- ✗
The IAM permissions for the Cloud Router are missing
Why it's wrong here
IAM permissions affect API calls, not BGP session establishment.
- ✗
The on-premises router is using a different BGP AS number than configured
Why it's wrong here
Different AS numbers would still allow BGP session establishment (eBGP). The session would come up but might affect route advertisement.
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 company's IT admin needs to give a contractor read-only access to production logs without sharing account credentials. Using role-based access control (RBAC) and temporary scoped permissions — not a permanent shared password — is the correct pattern. Questions like this test whether you can apply least-privilege access across cloud identity services.
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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Implementing Hybrid Interconnectivity — study guide chapter
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Implementing Hybrid Interconnectivity practice questions
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing Hybrid Interconnectivity — This question tests Implementing Hybrid Interconnectivity — Access ports place end devices into a single VLAN..
What is the correct answer to this question?
The correct answer is: The Cloud Router BGP IP address is not in the same subnet as the VLAN attachment — In Layer 2 Partner Interconnect, the customer must configure BGP sessions. The VLAN attachment type PARTNER requires the customer to manage BGP. Common issues include incorrect VLAN ID or IP addresses.
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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