- A
169.254.0.1
Google requires BGP peer IPs to be in the 169.254.0.0/16 range for Cloud VPN tunnels.
- B
10.0.0.1
Why wrong: Private IPs are not allowed for BGP over Cloud VPN; must use 169.254.x.x.
- C
The tunnel's external IP address
Why wrong: The tunnel's external IP is used for the VPN, not for BGP peering.
- D
The on-premises router's external IP address
Why wrong: External IPs are not used for BGP; BGP uses link-local addresses for the VPN.
Quick Answer
The answer is 169.254.0.1. This is the correct BGP peer IP because Google Cloud’s Cloud Router implementation automatically assigns the first usable address in the 169.254.0.0/16 link-local range for BGP peering over a VPN tunnel, while the on-premises router typically uses 169.254.0.2 as its peer. This design creates a deterministic point-to-point link-local BGP session, ensuring consistent routing without IP conflicts. On the Google Professional Cloud Network Engineer exam, this question tests your understanding of Cloud Router’s mandatory use of link-local addressing for VPN-based BGP sessions—a common trap is assuming you can use any private IP from RFC 1918 ranges. Remember that Cloud Router always takes the .1 address, so the on-premises side must be configured with .2. A simple memory tip: think of Cloud Router as the “first” peer, so it gets the “first” IP—169.254.0.1.
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 network engineer is configuring a Cloud Router for BGP peering with an on-premises router over a VPN tunnel. The on-premises router uses 169.254.x.x link-local addresses. Which BGP peer IP should the engineer use in the Cloud Router configuration?
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
169.254.0.1
The correct BGP peer IP is 169.254.0.1 because Cloud Router uses the first IP in the 169.254.0.0/16 link-local range for BGP peering over a VPN tunnel. This is required by Google Cloud's implementation, where the on-premises router must use a link-local address from the 169.254.0.0/16 range, and Cloud Router automatically assigns 169.254.0.1 as its own BGP peer IP. The on-premises router typically uses 169.254.0.2 as its BGP peer IP, ensuring a point-to-point link-local BGP session.
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.
- ✓
169.254.0.1
- ✗
10.0.0.1
- ✗
The tunnel's external IP address
- ✗
The on-premises router's external IP address
Why it's wrong here
External IPs are not used for BGP; BGP uses link-local addresses for the VPN.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that BGP peering over a VPN tunnel uses the tunnel's external IP addresses or private RFC 1918 addresses, but the correct answer requires knowledge that Google Cloud mandates link-local 169.254.x.x addresses for BGP sessions.
Detailed technical explanation
How to think about this question
Under the hood, Google Cloud Router uses RFC 3927 link-local addresses (169.254.0.0/16) to establish eBGP sessions over IPsec VPN tunnels, avoiding conflicts with customer VPC or on-premises addressing. The Cloud Router always uses 169.254.0.1, while the on-premises router must use 169.254.0.2 (or another address in the same /30 subnet) to form the BGP adjacency. This design ensures that BGP sessions are isolated from the underlying tunnel IPs and can survive tunnel endpoint changes without reconfiguration.
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 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.
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: 169.254.0.1 — The correct BGP peer IP is 169.254.0.1 because Cloud Router uses the first IP in the 169.254.0.0/16 link-local range for BGP peering over a VPN tunnel. This is required by Google Cloud's implementation, where the on-premises router must use a link-local address from the 169.254.0.0/16 range, and Cloud Router automatically assigns 169.254.0.1 as its own BGP peer IP. The on-premises router typically uses 169.254.0.2 as its BGP peer IP, ensuring a point-to-point link-local BGP session.
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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