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.
After configuring Cloud VPN with dynamic routing (BGP), you notice that on-premises routes are not appearing in Google Cloud. BGP sessions are established but no prefixes are exchanged. Cloud Router logs show: 'No route advertisement received'. On-premises BGP configuration shows 'network 10.0.0.0/8' and 'neighbor 10.1.1.1 remote-as 65000'. 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.
The 'network 10.0.0.0/8' command does not have a corresponding exact route in the on-premises routing table; also missing 'neighbor 10.1.1.1 activate' under BGP.
BGP requires the network to be in the routing table, and 'activate' is needed to start sending updates.
B
The on-premises router's BGP peer IP is not in the same subnet as the Cloud Router's interface.
Why wrong: They can be in different subnets as long as reachable.
C
The Cloud Router's BGP peer IP is not reachable from the on-premises router.
Why wrong: If unreachable, BGP sessions would not establish.
D
The BGP MD5 password is configured incorrectly on the on-premises router.
Why wrong: BGP sessions are established, so MD5 is not the issue.
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
The 'network 10.0.0.0/8' command does not have a corresponding exact route in the on-premises routing table; also missing 'neighbor 10.1.1.1 activate' under BGP.
Option A is correct because the on-premises BGP configuration uses the 'network 10.0.0.0/8' command, which requires an exact match in the local routing table to be advertised. Without a route for 10.0.0.0/8 (e.g., a connected or static route), BGP will not advertise it. Additionally, the 'neighbor 10.1.1.1 activate' command is missing under BGP, which is required to enable the exchange of prefixes with that neighbor. These two issues together prevent route advertisement to Google Cloud.
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.
✓
The 'network 10.0.0.0/8' command does not have a corresponding exact route in the on-premises routing table; also missing 'neighbor 10.1.1.1 activate' under BGP.
Why this is correct
BGP requires the network to be in the routing table, and 'activate' is needed to start sending updates.
Clue confirmation
The clue word "most likely" in the question point toward this answer.
Related concept
Read the scenario before looking for a memorised answer.
✗
The on-premises router's BGP peer IP is not in the same subnet as the Cloud Router's interface.
Why it's wrong here
They can be in different subnets as long as reachable.
✗
The Cloud Router's BGP peer IP is not reachable from the on-premises router.
The BGP MD5 password is configured incorrectly on the on-premises router.
Why it's wrong here
BGP sessions are established, so MD5 is not the issue.
Common exam traps
Common exam trap: answer the scenario, not the keyword
Google Cloud often tests the misconception that an established BGP session automatically implies route exchange, but candidates must remember that the 'network' command requires an exact routing table match and that 'neighbor activate' is needed under the address family to actually send prefixes.
Detailed technical explanation
How to think about this question
In BGP, the 'network' command advertises only prefixes that exactly match a route in the routing table (per RFC 4271). If the on-premises router has a summary route like 10.0.0.0/8 but the routing table contains a more specific route (e.g., 10.0.0.0/16), the /8 will not be advertised unless a static route for 10.0.0.0/8 is added. The 'neighbor activate' command is mandatory in Cisco IOS to enable prefix exchange for a specific neighbor under the BGP address family; without it, no updates are sent even if the session is up. In Google Cloud, Cloud Router expects to receive prefixes from the on-premises router to populate dynamic routes.
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 — 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: The 'network 10.0.0.0/8' command does not have a corresponding exact route in the on-premises routing table; also missing 'neighbor 10.1.1.1 activate' under BGP. — Option A is correct because the on-premises BGP configuration uses the 'network 10.0.0.0/8' command, which requires an exact match in the local routing table to be advertised. Without a route for 10.0.0.0/8 (e.g., a connected or static route), BGP will not advertise it. Additionally, the 'neighbor 10.1.1.1 activate' command is missing under BGP, which is required to enable the exchange of prefixes with that neighbor. These two issues together prevent route advertisement to Google Cloud.
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: "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?
Read the scenario before looking for a memorised answer.
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Question Discussion
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