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Implementing hybrid interconnectivity →easyMultiple ChoiceObjective-mapped

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.

Exhibit

Refer to the exhibit.

```json
{
  "routingMode": "DYNAMIC_ROUTING_MODE",
  "bgpRoutingMode": "GLOBAL",
  "advertiseMode": "CUSTOM",
  "advertisedGroups": [],
  "advertisedIpRanges": [
    {
      "range": "10.1.0.0/16",
      "description": "prod-subnet"
    },
    {
      "range": "10.2.0.0/16"
    }
  ]
}
```

An engineer configured a Cloud Router with the above settings. The VPC network has subnets 10.1.0.0/16 and 10.2.0.0/16, as well as subnets 10.3.0.0/16 and 10.4.0.0/16. The on-premises router is only receiving routes for 10.1.0.0/16 and 10.2.0.0/16 but not for 10.3.0.0/16 and 10.4.0.0/16. What is the cause?

Question 1easymultiple choice
Review the full subnetting walkthrough →

Exhibit

Refer to the exhibit.

```json
{
  "routingMode": "DYNAMIC_ROUTING_MODE",
  "bgpRoutingMode": "GLOBAL",
  "advertiseMode": "CUSTOM",
  "advertisedGroups": [],
  "advertisedIpRanges": [
    {
      "range": "10.1.0.0/16",
      "description": "prod-subnet"
    },
    {
      "range": "10.2.0.0/16"
    }
  ]
}
```

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 is set to custom advertisement mode, and the missing subnets are not included in the advertised IP ranges

Option C is correct because when a Cloud Router is configured in custom advertisement mode, it only advertises the specific CIDR ranges explicitly listed in the 'Advertised IP ranges' field. Since the missing subnets (10.3.0.0/16 and 10.4.0.0/16) are not included in that list, they are not propagated via BGP to the on-premises router, even though they exist in the VPC.

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 BGP session is not established

    Why it's wrong here

    If BGP were down, no routes would be received; the on-premises router does receive some routes.

  • ✗

    The Cloud Router is in global routing mode, which does not advertise all subnets

    Why it's wrong here

    Global routing mode is about inter-region traffic, not advertisement scope.

  • ✓

    The Cloud Router is set to custom advertisement mode, and the missing subnets are not included in the advertised IP ranges

    Why this is correct

    Custom mode requires explicit specification of ranges to advertise; only listed ranges are advertised.

    Related concept

    Read the scenario before looking for a memorised answer.

  • ✗

    The on-premises router has a filter that blocks the other routes

    Why it's wrong here

    The exhibit focuses on Cloud Router configuration; on-premises filtering is not indicated.

Common exam traps

Common exam trap: answer the scenario, not the keyword

Google Cloud often tests the distinction between default advertisement mode (which automatically advertises all VPC subnets) and custom advertisement mode (which requires explicit configuration), leading candidates to overlook the fact that missing routes are due to an incomplete custom list rather than a BGP session issue or routing mode setting.

Detailed technical explanation

How to think about this question

Cloud Router uses BGP to exchange routes with on-premises routers. In custom advertisement mode, the router only advertises the prefixes you explicitly define, overriding the default behavior of advertising all VPC subnet routes. This is useful for controlling route propagation in complex hybrid networks, but it requires careful management to ensure all desired subnets are listed. The 'Advertised IP ranges' field can include both VPC subnets and custom prefixes, and any omission will result in those prefixes not being sent in BGP UPDATE messages.

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.

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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: The Cloud Router is set to custom advertisement mode, and the missing subnets are not included in the advertised IP ranges — Option C is correct because when a Cloud Router is configured in custom advertisement mode, it only advertises the specific CIDR ranges explicitly listed in the 'Advertised IP ranges' field. Since the missing subnets (10.3.0.0/16 and 10.4.0.0/16) are not included in that list, they are not propagated via BGP to the on-premises router, even though they exist in the VPC.

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

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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.