PCNE Implementing network security Practice Question
A company has two VPCs in the same project: VPC-A (10.0.0.0/16) and VPC-B (10.1.0.0/16). They want to allow SSH from VPC-A to instances in VPC-B. The network admin creates a firewall rule with source range 10.0.0.0/16 and protocol tcp:22, but connectivity fails. What is the most likely cause?
⚠ Common exam trap
Google Cloud often tests the misconception that firewall rules are applied at the source network or that rules are global across VPCs, when in fact each VPC has its own independent set of firewall rules and ingress rules must be in the destination VPC.
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 rule is created in VPC-A instead of VPC-B.
Firewall rules in Google Cloud are applied at the network level, not the instance level. To allow inbound SSH traffic from VPC-A to instances in VPC-B, the firewall rule must be created in VPC-B (the destination network) with the source range set to 10.0.0.0/16. Creating the rule in VPC-A would only affect traffic destined for instances in VPC-A, not VPC-B.
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 rule is created in VPC-A instead of VPC-B.
Why this is correct
Firewall rules apply to the VPC they are created in. An ingress rule for VPC-B must be created in VPC-B.
- ✗
The source range should be 10.0.0.0/8.
Why it's wrong here
The source range is already correct for VPC-A.
- ✗
The target tag is not specified.
Why it's wrong here
Target tags are optional; if not specified, the rule applies to all instances.
- ✗
The source tag is missing.
Why it's wrong here
Tags are not required when using source ranges.
Go deeper
Related to this question
About these practice questions
This PCNE question is part of Courseiva's 961-question bank — original exam-style content with full explanations and wrong-answer analysis, never real exam questions or exam dumps. Learn why practice questions differ from exam dumps →
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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.