Auto Scaling Groups

5 minutes 5 Questions

Auto Scaling Groups (ASGs) are the core component of AWS Auto Scaling. They manage the lifecycle of Amazon EC2 instances and ensure that the desired number of instances is running in your specified availability zones. ASGs help maintain the overall health and performance of your application by dynamically scaling instances according to your desired rules and policies. With ASGs, you can configure the minimum, maximum, and desired capacity of instances, as well as custom scaling policies based on CloudWatch alarms or predefined metrics such as CPU utilization or network throughput.

AWS Solution Architect - Auto Scaling Groups

Auto Scaling Groups
An Auto Scaling group is a key component of AWS, designed to ensure the optimum number of running instances according to user-defined policies. The importance revolves around its ability to maintain high availability and automatically scale your applications in response to changing demands.
How it works:
It works by launching or terminating instances based on user-defined policies, health status checks, and schedules.
Exam Tips: Answering Questions on Auto Scaling Groups
When answering questions on Auto Scaling Groups, be sure to remember the following:
1. Understand the concept of 'desired capacity', 'minimum' and 'maximum'.
2. Remember that instances will be added first from On-Demand and then Spot instances.
3. Health Checks are crucial; they determine the instances' state and dictate if new ones should be initiated.
4. Keep in mind that scaling cannot happen past the specified maximum limit.
5. Recognize that Auto Scaling groups can span across multiple Availability Zones.

Test mode:

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Question 1

Your website has an increase in traffic during specific hours of the day. To optimize instance capacity during peak hours, you need the Auto Scaling Group to increase the number of instances early morning and decrease them by evening. Which feature can help achieve this?

Dynamic Scaling Target Tracking Scaling Policy Manual Scaling Scheduled Scaling

Correct Answer: Scheduled Scaling

Scheduled Scaling allows you to increase or decrease the number of instances in an Auto Scaling group based on a predefined schedule. By specifying the times when the scale-out or scale-in occurs, you can optimize resources efficiently for predictable traffic patterns.

Question 2

Your company has a web application running on multiple EC2 instances. To ensure high availability and fault tolerance, you have set up an Auto Scaling Group (ASG) with instances across multiple Availability Zones. Recently, your company experienced a spike in traffic, causing unhealthy instances. Which ASG configuration change will automatically replace the unhealthy instances?

Decrease the Minimum number of instances Change the Health Check Type to 'ELB' Increase the Desired capacity Enable the Health Check Type as 'EC2' and set a grace period

Correct Answer: Enable the Health Check Type as 'EC2' and set a grace period

By setting the Health Check Type to 'EC2', the ASG detects unhealthy instances based on EC2 instance status checks. Using the health check grace period, the ASG gives ample time to launch an instance and become healthy before getting marked as unhealthy.

Question 3

You are a Solutions Architect in a global company that hosts an E-commerce website. You have multiple EC2 instances running your web server with an ELB distributing traffic. To avoid service interruptions, you configure an ASG to monitor traffic. Which policy would be ideal for scaling up or down based on traffic?

Simple Scaling Policy Step Scaling Policy Target Tracking Scaling Policy Instance Warm-up Policy

Correct Answer: Target Tracking Scaling Policy

Target Tracking Scaling Policies provide a convenient way to scale Auto Scaling groups based on dynamic traffic patterns. This policy scales based on predefined thresholds and tracks a specific metric (e.g., CPU utilization).

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