Google ACE Practice Question: Ensuring Successful Operation of a Cloud Solution
You need to attach an existing 100 GB persistent disk named 'my-disk' to a Compute Engine instance 'web-server-1'. What is the correct command?
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
✓
gcloud compute instances attach-disk web-server-1 --disk my-disk
The command is gcloud compute instances attach-disk.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
gcloud compute instances add-disk web-server-1 --disk my-disk
Why it's wrong here
The gcloud compute instances command group does not include an add-disk subcommand; the correct verb for attaching a persistent disk is attach-disk. Because add-disk is not a valid operation, this command will fail with an unrecognized verb error rather than attaching the existing 100 GB disk. Always verify the subcommand name when working with gcloud.
- ✗
gcloud compute disks attach my-disk --instance web-server-1
Why it's wrong here
This command incorrectly places the operation under the disks subcommand, using attach as a verb. In gcloud, attaching a disk is an instance-level operation, so the primary resource must be the instance, not the disk. The disks subcommand manages persistent disk lifecycle - create, delete, snapshot, resize - and does not have an attach verb, so this command is invalid.
- ✗
gcloud compute disks create my-disk --instance web-server-1
Why it's wrong here
This is a create operation, not an attachment: gcloud compute disks create provisions a brand new persistent disk, but you already have an existing 100 GB disk to attach. The --instance flag is not recognized by disks create, and the command would either fail or create an unrelated disk. To attach the existing disk, use the instances attach-disk subcommand.
- ✓
gcloud compute instances attach-disk web-server-1 --disk my-disk
Why this is correct
This is the correct command. The attach-disk subcommand belongs to gcloud compute instances, takes web-server-1 as the resource, and uses --disk my-disk to specify the existing persistent disk to attach. It associates the already provisioned 100 GB disk with the instance, and requires the disk and instance to be in the same zone (or use --zone if they are not set).
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Google Compute Engine
Key term
Compute Engine
Compute Engine is Google Cloud's Infrastructure-as-a-Service (IaaS) offering that lets you create and run virtual machines on Google's infrastructure.
Key term
Persistent Disk
Persistent Disk is a durable, high-performance block storage service for Google Cloud virtual machines that retains data even after the VM is shut down or deleted.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ACE 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 ACE exam.