PAS-C01 Auto Scaling lifecycle hooks Practice Question
A company runs SAP on AWS and uses a distributed deployment with multiple application servers in an Auto Scaling group. They want to ensure that when a new instance is launched, it is automatically registered with the SAP Central Services instance. Which approach should they use?
⚠ Common exam trap
Candidates often confuse user data with lifecycle hooks. User data runs at boot but does not pause the instance lifecycle, so it cannot guarantee registration before the instance becomes healthy. A lifecycle hook with a Lambda function ensures registration completes before the instance is marked 'InService'.
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
✓
Use an Auto Scaling lifecycle hook that triggers a Lambda function to perform the registration when the instance enters the 'InService' state.
Auto Scaling lifecycle hooks allow you to pause an instance during launch and perform custom actions, such as invoking a Lambda function to register the instance with SAP Central Services, before the instance is placed in service. Option A is incorrect because user data runs at boot but does not integrate with the Auto Scaling lifecycle to ensure registration completes before the instance becomes healthy. Option B is incorrect because CloudFormation is used for infrastructure provisioning and not for per-instance registration triggered by scaling events. Option C is incorrect because AWS Systems Manager Run Command is not automatically triggered during Auto Scaling launches; it requires manual or scheduled execution.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Configure the user data script to run the registration command on instance boot.
Why it's wrong here
User data runs at boot before the instance is fully ready; it does not wait for registration to complete, so the instance may become healthy before registration finishes.
- ✗
Use an AWS CloudFormation template to create the instance and include the registration in the template.
Why it's wrong here
CloudFormation handles initial resource creation, not ongoing Auto Scaling events. It cannot automatically register instances launched by a scaling policy.
- ✗
Use AWS Systems Manager Run Command to register the instance after it launches.
Why it's wrong here
AWS Systems Manager Run Command is used for ad-hoc or scheduled commands, not for automatic execution at instance launch.
- ✓
Use an Auto Scaling lifecycle hook that triggers a Lambda function to perform the registration when the instance enters the 'InService' state.
Why this is correct
An Auto Scaling lifecycle hook pauses the instance in the 'InService' state and triggers a Lambda function to perform registration, ensuring the instance is registered before it receives traffic.
Quick reference
Cloud Service Model Comparison
| Model | You Manage | Provider Manages | Examples |
|---|---|---|---|
| IaaS | OS, runtime, apps, data | Hardware, hypervisor, networking | EC2, Azure VMs, GCP Compute Engine |
| PaaS | Apps and data | OS, runtime, middleware, hardware | Elastic Beanstalk, Azure App Service |
| SaaS | Data and settings only | Everything else | Microsoft 365, Salesforce, Workday |
| FaaS / Serverless | Function code only | Infra, scaling, runtime | Lambda, Azure Functions, Cloud Run |
| CaaS | Containers and apps | Kubernetes, OS, hardware | EKS, AKS, GKE |
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This PAS-C01 practice question is part of Courseiva's free Amazon Web Services 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 PAS-C01 exam.