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AWScloud~10 mins

Reliability pillar principles in AWS - Interactive Code Practice

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Practice - 5 Tasks
Answer the questions below
1fill in blank
easy

Complete the code to specify the AWS service that helps recover from infrastructure failures automatically.

AWS
Use AWS [1] to automatically replace unhealthy instances in your application.
Drag options to blanks, or click blank then click option'
AAuto Scaling
BLambda
CS3
DCloudFormation
Attempts:
3 left
💡 Hint
Common Mistakes
Choosing CloudFormation which is for infrastructure as code, not automatic recovery.
Selecting S3 which is storage, not related to instance health.
Picking Lambda which is for serverless functions, not instance replacement.
2fill in blank
medium

Complete the code to choose the AWS feature that helps distribute traffic across multiple resources.

AWS
Use [1] to balance incoming traffic and improve fault tolerance.
Drag options to blanks, or click blank then click option'
AElastic Load Balancer
BCloudWatch
CCloudTrail
DIAM
Attempts:
3 left
💡 Hint
Common Mistakes
Choosing CloudTrail which is for logging, not traffic distribution.
Selecting CloudWatch which monitors resources but does not distribute traffic.
Picking IAM which manages permissions, unrelated to traffic.
3fill in blank
hard

Fix the error in the code to correctly enable multi-AZ deployment for high availability.

AWS
Create an RDS instance with MultiAZ set to [1].
Drag options to blanks, or click blank then click option'
A"false"
BFalse
Ctrue
DTrue
Attempts:
3 left
💡 Hint
Common Mistakes
Using lowercase 'true' or 'false' as strings instead of boolean values.
Using quotes around boolean values.
4fill in blank
hard

Fill both blanks to create a CloudWatch alarm that triggers when CPU usage is above 80%.

AWS
alarm = cloudwatch.put_metric_alarm(MetricName='CPUUtilization', Threshold=[1], ComparisonOperator='[2]')
Drag options to blanks, or click blank then click option'
A80
BGreaterThanThreshold
CLessThanThreshold
D70
Attempts:
3 left
💡 Hint
Common Mistakes
Using 'LessThanThreshold' which triggers alarm when usage is below threshold.
Setting threshold to 70 instead of 80.
5fill in blank
hard

Fill all three blanks to define a lifecycle policy that transitions objects to Glacier after 30 days and expires after 365 days.

AWS
lifecycle = {
  'Rules': [{
    'ID': 'ArchiveRule',
    'Status': '[1]',
    'Transitions': [{'Days': [2], 'StorageClass': '[3]'}],
    'Expiration': {'Days': 365}
  }]
}
Drag options to blanks, or click blank then click option'
AEnabled
BDisabled
CGLACIER
DSTANDARD_IA
E30
Attempts:
3 left
💡 Hint
Common Mistakes
Setting status to 'Disabled' which turns off the rule.
Using 'STANDARD_IA' instead of 'GLACIER' for archiving.
Incorrect number of days for transition.

Practice

(1/5)
1. What is the main goal of the Reliability pillar in cloud architecture?
easy
A. To reduce the cost of cloud services
B. To keep systems working well and recover quickly from failures
C. To improve the visual design of applications
D. To increase the speed of data processing

Solution

  1. Step 1: Understand the purpose of the Reliability pillar

    The Reliability pillar focuses on system uptime and fast recovery from issues.
  2. Step 2: Compare options with the pillar's goal

    Only To keep systems working well and recover quickly from failures matches the goal of keeping systems working well and recovering quickly.
  3. Final Answer:

    To keep systems working well and recover quickly from failures -> Option B
  4. Quick Check:

    Reliability = keep systems working and recover fast [OK]
Hint: Reliability means uptime and fast recovery [OK]
Common Mistakes:
  • Confusing reliability with cost savings
  • Thinking reliability is about design or speed only
  • Ignoring recovery after failure
2. Which AWS service is commonly used to monitor system health and trigger alerts for reliability?
easy
A. Amazon S3
B. Amazon EC2
C. Amazon CloudWatch
D. AWS Lambda

Solution

  1. Step 1: Identify monitoring services in AWS

    Amazon CloudWatch is designed to monitor resources and send alerts.
  2. Step 2: Eliminate unrelated services

    Amazon S3 is for storage, Lambda for running code, EC2 for servers, so they don't primarily monitor health.
  3. Final Answer:

    Amazon CloudWatch -> Option C
  4. Quick Check:

    Monitoring and alerts = CloudWatch [OK]
Hint: CloudWatch monitors and alerts in AWS [OK]
Common Mistakes:
  • Choosing storage or compute services instead of monitoring
  • Confusing Lambda with monitoring
  • Not knowing CloudWatch's role
3. Consider this AWS setup: An application uses multiple Availability Zones (AZs) with automatic failover. What is the expected behavior if one AZ fails?
medium
A. The application performance improves in the failed AZ
B. The application stops working until the failed AZ is restored
C. The application data is lost permanently
D. Traffic automatically shifts to healthy AZs to keep the app running

Solution

  1. Step 1: Understand multi-AZ and failover

    Using multiple AZs with failover means if one AZ fails, traffic moves to others automatically.
  2. Step 2: Analyze each option

    The application stops working until the failed AZ is restored is false because failover prevents downtime. The application data is lost permanently is false because data is replicated. The application performance improves in the failed AZ is illogical as failed AZ cannot improve performance.
  3. Final Answer:

    Traffic automatically shifts to healthy AZs to keep the app running -> Option D
  4. Quick Check:

    Multi-AZ failover = automatic traffic shift [OK]
Hint: Failover shifts traffic to healthy zones automatically [OK]
Common Mistakes:
  • Assuming app stops during AZ failure
  • Thinking data is lost without backups
  • Believing failed AZ improves performance
4. You have a backup system that runs daily but sometimes misses backups due to network issues. What is the best way to improve reliability?
medium
A. Add monitoring and alerts to detect backup failures immediately
B. Reduce backup frequency to weekly
C. Ignore the missed backups since they are rare
D. Delete old backups to save space

Solution

  1. Step 1: Identify the problem with backup reliability

    Missed backups reduce reliability and risk data loss.
  2. Step 2: Choose a solution that improves detection and response

    Adding monitoring and alerts helps detect failures quickly and fix them, improving reliability.
  3. Final Answer:

    Add monitoring and alerts to detect backup failures immediately -> Option A
  4. Quick Check:

    Detect failures fast = add monitoring and alerts [OK]
Hint: Monitor backups to catch failures early [OK]
Common Mistakes:
  • Ignoring backup failures
  • Reducing backup frequency which lowers reliability
  • Deleting backups without ensuring new ones exist
5. A company wants to design a highly reliable web application on AWS. Which combination of strategies best supports the Reliability pillar?
hard
A. Deploy across multiple Availability Zones, automate backups, and enable CloudWatch alarms
B. Use single Availability Zone, manual backups, and no monitoring
C. Use only on-premises servers with no cloud services
D. Deploy in one region with no failover and no testing

Solution

  1. Step 1: Identify key reliability strategies

    Reliability requires redundancy (multi-AZ), automated backups, and monitoring with alerts.
  2. Step 2: Evaluate each option

    Deploy across multiple Availability Zones, automate backups, and enable CloudWatch alarms includes all key strategies. Options A, C, and D lack redundancy, automation, or monitoring, reducing reliability.
  3. Final Answer:

    Deploy across multiple Availability Zones, automate backups, and enable CloudWatch alarms -> Option A
  4. Quick Check:

    Multi-AZ + backups + monitoring = high reliability [OK]
Hint: Combine multi-AZ, backups, and monitoring for reliability [OK]
Common Mistakes:
  • Choosing single AZ or no monitoring
  • Ignoring automation and failover
  • Relying only on on-premises servers
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