hardMultiple ChoiceObjective-mapped
CV0-004 Practice Question: Refer to the exhibit
Exhibit
$ gcloud compute instances describe instance-1 --zone=us-central1-a
...
networkInterfaces:
- accessConfigs:
- name: external-nat
type: ONE_TO_ONE_NAT
natIP: 35.123.45.67
network: https://www.googleapis.com/compute/v1/projects/my-project/global/networks/default
subnetwork: https://www.googleapis.com/compute/v1/projects/my-project/regions/us-central1/subnetworks/default
networkIP: 10.128.0.2
...Refer to the exhibit. A cloud administrator deployed a Compute Engine instance in the default VPC. The instance has a public IP but cannot be accessed via SSH from the internet. The firewall rules allow ingress on port 22 from 0.0.0.0/0. What is the most likely cause?
⚠ Common exam trap
Google Cloud often tests the misconception that a firewall rule allowing all traffic (0.0.0.0/0) automatically applies to all instances, but in Google Cloud, target tags must match for the rule to be effective.
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 instance does not have a firewall tag matching the SSH rule.
The most likely cause is that the instance does not have a firewall tag matching the SSH rule. In Google Cloud, firewall rules can be applied to target instances using network tags. Even if the rule allows ingress on port 22 from 0.0.0.0/0, it will only apply to instances that have the corresponding tag (e.g., 'allow-ssh'). Without the tag, the rule is not enforced on the instance, blocking SSH access despite the public IP.
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 instance does not have a firewall tag matching the SSH rule.
Why this is correct
If the SSH rule is targeted to a specific network tag that the instance lacks, the rule does not apply.
- ✗
The instance is not assigned to a service account.
Why it's wrong here
Service accounts are for API permissions, not for firewall rule application.
- ✗
The subnetwork does not have an external IP range.
Why it's wrong here
The exhibit shows a public IP assigned, so the subnetwork supports external IPs.
- ✗
The instance is running an incompatible OS.
Why it's wrong here
An incompatible OS would affect the SSH daemon, but the firewall rule would still be in place.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This CV0-004 practice question is part of Courseiva's free CompTIA 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 CV0-004 exam.