ANS-C01 Network Implementation Practice Question
A company runs a critical application on EC2 instances behind an Application Load Balancer. They need to ensure that if an instance fails health checks, it is automatically terminated and replaced. Which AWS service should they use?
⚠ Common exam trap
The trap here is that candidates might choose Amazon CloudWatch (Option D) because they know CloudWatch can monitor health checks and trigger actions, but they overlook that CloudWatch alone cannot directly terminate and replace EC2 instances—it requires additional automation (e.g., Lambda or Auto Scaling), making Auto Scaling the correct and complete answer for automatic replacement.
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
✓
Auto Scaling group
An Auto Scaling group (Option C) is the correct service because it automatically replaces unhealthy EC2 instances by integrating with the Application Load Balancer's health checks. When an instance fails the configured health check (e.g., HTTP 5xx or TCP timeout), the Auto Scaling group marks it as unhealthy, terminates it, and launches a new instance to maintain the desired capacity. This lifecycle management is a core feature of Auto Scaling groups, not available in the other options.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
AWS Lambda
Why it's wrong here
Lambda could be used with custom automation, but it is not the native service for this purpose.
- ✗
EC2 Instance Connect
Why it's wrong here
EC2 Instance Connect allows SSH access but does not manage instance health or replacement.
- ✓
Auto Scaling group
Why this is correct
Auto Scaling groups can use ELB health checks to automatically replace unhealthy instances.
- ✗
Amazon CloudWatch
Why it's wrong here
CloudWatch can monitor and alarm but cannot automatically terminate and replace instances.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This ANS-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 ANS-C01 exam.