- A
Change the BGP ASN on the Cloud Router to a different number
Why wrong: They have verified the ASNs; this step might be needed only if ASN mismatch, but they said they are same. However, if same ASN, BGP may need 'allow-as' or 'as-override', but the question indicates they've already checked, so not the most likely next step.
- B
Ensure the on-premises router has a route to the Cloud Router's BGP peer IP address
Without a return route, BGP packets cannot reach the Cloud Router.
- C
Increase the BGP hold timer on the Cloud Router
Why wrong: Changing hold timer would not affect session establishment if the problem is connectivity.
- D
Change the BGP keepalive interval to 10 seconds
Why wrong: Keepalive interval is not related to CONNECT state.
- E
Verify the Cloud VPN tunnel is established and passing traffic
A non-working tunnel can prevent BGP from establishing.
Quick Answer
The answer is to verify the Cloud VPN tunnel is established and passing traffic. When a BGP session is stuck in the CONNECT state due to a missing route to the peer IP, the router is actively attempting a TCP handshake on port 179 but receives no response, typically because the underlying VPN tunnel is down or not forwarding packets. On the Google Professional Cloud Network Engineer exam, this scenario tests your understanding that BGP relies on a functional underlay network; a common trap is to focus only on BGP configuration errors while overlooking the tunnel status. Remember that CONNECT means the router is trying to reach the peer—if the tunnel is broken, no route exists, and SYN packets are silently dropped. A useful memory tip: CONNECT = Check the Overlay Network, Not Just Config Errors.
PCNE Implementing hybrid interconnectivity Practice Question
This PCNE practice question tests your understanding of implementing hybrid interconnectivity. The scenario asks you to isolate a root cause — eliminate options that address a different problem before choosing. 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 troubleshooting a BGP session between an on-premises router and a Cloud Router. The BGP session state is 'CONNECT' and never transitions to 'ESTABLISHED'. The engineer has verified that the Cloud Router and on-premises router have the same BGP ASN, and that the peer IP addresses are correctly configured. Which two additional steps should the engineer take to resolve this issue? (Choose TWO.)
Clue words in this question
Noticing these words before you look at the options changes how you read each choice.
Clue:
"never"Why it matters: Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
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
Ensure the on-premises router has a route to the Cloud Router's BGP peer IP address
When the BGP session state is stuck in 'CONNECT', it indicates that the router is actively trying to initiate a TCP connection to the peer but is not receiving a response. For BGP to establish a TCP session (port 179), the on-premises router must have a valid IP route to the Cloud Router's BGP peer IP address. Without this route, TCP SYN packets are dropped, preventing the session from transitioning to 'ESTABLISHED'.
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.
- ✗
Change the BGP ASN on the Cloud Router to a different number
Why it's wrong here
They have verified the ASNs; this step might be needed only if ASN mismatch, but they said they are same. However, if same ASN, BGP may need 'allow-as' or 'as-override', but the question indicates they've already checked, so not the most likely next step.
- ✓
Ensure the on-premises router has a route to the Cloud Router's BGP peer IP address
Why this is correct
Without a return route, BGP packets cannot reach the Cloud Router.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
- ✗
Increase the BGP hold timer on the Cloud Router
Why it's wrong here
Changing hold timer would not affect session establishment if the problem is connectivity.
- ✗
Change the BGP keepalive interval to 10 seconds
Why it's wrong here
Keepalive interval is not related to CONNECT state.
- ✓
Verify the Cloud VPN tunnel is established and passing traffic
Why this is correct
A non-working tunnel can prevent BGP from establishing.
Clue confirmation
The clue word "never" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that BGP session issues in the 'CONNECT' state are caused by BGP timer or ASN misconfigurations, when the real root cause is almost always a lack of IP reachability (missing route or tunnel failure) preventing the TCP connection from forming.
Detailed technical explanation
How to think about this question
The 'CONNECT' state in BGP means the router is waiting for the TCP three-way handshake to complete. If the TCP SYN packet is sent but no SYN-ACK is received, the session remains in CONNECT (or transitions to ACTIVE). Common causes include missing routes, ACLs blocking TCP port 179, or the peer not listening on the correct IP. In Google Cloud, Cloud Routers use BGP over IPsec VPN tunnels, so the VPN tunnel must be up and passing traffic for the BGP peer IP to be reachable; otherwise, the on-premises router cannot complete the TCP handshake.
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.
Identify which exam domain this question belongs to, review the core concept, then practise similar questions from the same domain.
- →
Implementing hybrid interconnectivity — study guide chapter
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FAQ
Questions learners often ask
What does this PCNE question test?
Implementing hybrid interconnectivity — This question tests Implementing hybrid interconnectivity — Read the scenario before looking for a memorised answer..
What is the correct answer to this question?
The correct answer is: Ensure the on-premises router has a route to the Cloud Router's BGP peer IP address — When the BGP session state is stuck in 'CONNECT', it indicates that the router is actively trying to initiate a TCP connection to the peer but is not receiving a response. For BGP to establish a TCP session (port 179), the on-premises router must have a valid IP route to the Cloud Router's BGP peer IP address. Without this route, TCP SYN packets are dropped, preventing the session from transitioning to 'ESTABLISHED'.
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.
Are there clue words in this question I should notice?
Yes — watch for: "never". Absolute qualifier. True only if the statement has zero exceptions — be cautious of options that seem obvious but break down in edge cases.
What is the key concept behind this question?
Read the scenario before looking for a memorised answer.
About these practice questions
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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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