High availability design patterns in AWS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a highly available web server using AWS Elastic Load Balancer.

AWS

resource "aws_elb" "web_elb" {
  name               = "web-elb"
  availability_zones = ["us-east-1a", "us-east-1b"]
  listener {
    instance_port     = 80
    instance_protocol = "HTTP"
    lb_port           = 80
    lb_protocol       = [1]
  }
}

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AHTTPS

BSSL

CTCP

DHTTP

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing HTTPS for port 80 causes connection errors.

Using TCP or SSL protocols for HTTP traffic is incorrect.

The load balancer protocol should match the instance protocol for HTTP traffic, so "HTTP" is correct.

2fill in blank

medium

Complete the code to define an Auto Scaling group with a minimum of 2 instances for high availability.

AWS

resource "aws_autoscaling_group" "web_asg" {
  name                      = "web-asg"
  max_size                  = 5
  min_size                  = [1]
  desired_capacity          = 3
  launch_configuration      = aws_launch_configuration.web_lc.name
  availability_zones        = ["us-east-1a", "us-east-1b"]
}

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A1

B2

C0

D3

Attempts:

3 left

💡 Hint

Common Mistakes

Setting min_size to 1 risks downtime if that instance fails.

Setting min_size to 0 disables instances.

Setting min_size to 2 ensures at least two instances run for high availability.

3fill in blank

hard

Fix the error in the Route 53 health check configuration to improve availability.

AWS

resource "aws_route53_health_check" "web_health_check" {
  fqdn              = "example.com"
  port              = 80
  type              = [1]
  failure_threshold = 3
}

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AHTTP

BHTTPS

CTCP

DSSL

Attempts:

3 left

💡 Hint

Common Mistakes

Using HTTPS or SSL on port 80 causes health check to fail.

Using TCP does not check HTTP response status.

The health check type should be HTTP for port 80 to correctly monitor web server health.

4fill in blank

hard

Fill both blanks to configure a multi-AZ RDS instance for high availability.

AWS

resource "aws_db_instance" "mydb" {
  allocated_storage    = 20
  engine               = "mysql"
  instance_class       = [1]
  multi_az             = [2]
  identifier           = "mydb"
  username             = "admin"
  password             = "password"
  skip_final_snapshot  = true
}

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Adb.m5.large

Bdb.t2.micro

Ctrue

Dfalse

Attempts:

3 left

💡 Hint

Common Mistakes

Using a micro instance class is not recommended for production.

Setting multi_az to false disables high availability.

Use a suitable instance class like db.m5.large and set multi_az to true for high availability.

5fill in blank

hard

Fill all three blanks to create a CloudWatch alarm that triggers when CPU usage is high.

AWS

resource "aws_cloudwatch_metric_alarm" "high_cpu" {
  alarm_name          = "high_cpu_alarm"
  comparison_operator = [1]
  evaluation_periods  = 2
  metric_name         = "CPUUtilization"
  namespace           = "AWS/EC2"
  period              = 300
  statistic           = [2]
  threshold           = 80
  alarm_actions       = [aws_sns_topic.alerts.arn]
  dimensions = {
    InstanceId = [3]
  }
}

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AGreaterThanThreshold

BAverage

Cvar.instance_id

DLessThanThreshold

Attempts:

3 left

💡 Hint

Common Mistakes

Using LessThanThreshold triggers alarm on low CPU, which is incorrect.

Using Sum or Maximum instead of Average may not reflect typical usage.

Not specifying the instance ID dimension causes alarm to apply to all instances.

The alarm triggers when CPU usage is greater than the threshold using average metric and the instance ID dimension.