- A
You must create a separate Cloud Router for each VLAN attachment.
Why wrong: A single Cloud Router can manage multiple VLAN attachments.
- B
You can configure the Cloud Router to advertise the same IP prefixes over both VLAN attachments.
Advertising the same prefixes over multiple VLANs enables load balancing.
- C
You should use BGP MED to load balance outbound traffic from Google Cloud.
Why wrong: MED influences inbound traffic; for outbound, you use AS path prepending or weight.
- D
You can use the same BGP ASN for both VLAN attachments.
It is common to use the same ASN for multiple BGP sessions on the same Cloud Router.
- E
Load balancing across VLAN attachments requires a single BGP session.
Why wrong: Load balancing requires multiple BGP sessions, one per VLAN attachment.
Quick Answer
The answer is that using the same BGP ASN for both VLAN attachments is correct because a Cloud Router can advertise identical IP prefixes over multiple VLAN attachments, enabling load balancing. This works by leveraging Equal-Cost Multi-Path (ECMP) routing, which distributes outbound traffic across the attachments when BGP attributes like AS path length and MED are equal, ensuring the paths are perceived as equally preferred. On the Google Professional Cloud Network Engineer exam, this tests your understanding of how BGP load balancing across VLAN attachments functions with Dedicated Interconnect, often appearing as a trap where candidates mistakenly think different ASNs are required for redundancy. A common pitfall is confusing BGP best-path selection with ECMP—remember that identical attributes, not different ASNs, are the key to balancing traffic. Memory tip: "Same ASN, same path length, equal cost—traffic splits with equal strength."
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.
A company is designing a hybrid network using Dedicated Interconnect. They want to configure BGP for load balancing across multiple VLAN attachments. Which TWO statements are correct?
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
You can configure the Cloud Router to advertise the same IP prefixes over both VLAN attachments.
Option B is correct because a Cloud Router can advertise the same IP prefixes over multiple VLAN attachments to enable load balancing. This allows Google Cloud to use ECMP (Equal-Cost Multi-Path) routing to distribute outbound traffic across the two VLAN attachments, as long as the BGP attributes (e.g., AS path length, MED) are equal.
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.
- ✗
You must create a separate Cloud Router for each VLAN attachment.
Why it's wrong here
A single Cloud Router can manage multiple VLAN attachments.
- ✓
You can configure the Cloud Router to advertise the same IP prefixes over both VLAN attachments.
Why this is correct
Advertising the same prefixes over multiple VLANs enables load balancing.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
You should use BGP MED to load balance outbound traffic from Google Cloud.
Why it's wrong here
MED influences inbound traffic; for outbound, you use AS path prepending or weight.
- ✓
You can use the same BGP ASN for both VLAN attachments.
Why this is correct
It is common to use the same ASN for multiple BGP sessions on the same Cloud Router.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Load balancing across VLAN attachments requires a single BGP session.
Why it's wrong here
Load balancing requires multiple BGP sessions, one per VLAN attachment.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that BGP MED controls outbound traffic, but in reality, MED is a hint for inbound path selection, while outbound load balancing relies on equal BGP attributes and ECMP.
Detailed technical explanation
How to think about this question
When using Dedicated Interconnect with multiple VLAN attachments, each attachment establishes its own BGP session. The Cloud Router advertises the same IP prefixes with identical BGP attributes (AS path, MED, local preference) over each session, enabling Google Cloud to perform ECMP on outbound traffic. This is analogous to using multiple equal-cost paths in traditional routing, where the router forwards packets across links in a round-robin or hash-based manner.
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 startup's cloud architect reviews their monthly bill and notices costs are higher than expected for a long-running batch job. Switching from on-demand instances to Reserved Instances — or using Spot/Preemptible VMs — can reduce compute costs by up to 72 %. Questions like this test whether you understand the tradeoffs between commitment, flexibility, and cost across cloud pricing models.
What to study next
Got this wrong? Here's your next step.
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FAQ
Questions learners often ask
What does this PCNE question test?
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: You can configure the Cloud Router to advertise the same IP prefixes over both VLAN attachments. — Option B is correct because a Cloud Router can advertise the same IP prefixes over multiple VLAN attachments to enable load balancing. This allows Google Cloud to use ECMP (Equal-Cost Multi-Path) routing to distribute outbound traffic across the two VLAN attachments, as long as the BGP attributes (e.g., AS path length, MED) are equal.
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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Last reviewed: Jun 30, 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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