Why cost management prevents surprises in DynamoDB - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create a billing alarm for DynamoDB usage.

DynamoDB

aws cloudwatch put-metric-alarm --alarm-name DynamoDBUsageAlarm --metric-name [1] --namespace AWS/Billing --statistic Maximum --period 21600 --threshold 100 --comparison-operator GreaterThanThreshold --evaluation-periods 1 --alarm-actions arn:aws:sns:us-east-1:123456789012:NotifyMe

Drag options to blanks, or click blank then click option'

AConsumedReadCapacityUnits

BThrottledRequests

CProvisionedWriteCapacityUnits

DEstimatedCharges

Attempts:

3 left

💡 Hint

Common Mistakes

Choosing a capacity metric instead of a billing metric.

Using a metric that tracks usage but not cost.

The EstimatedCharges metric tracks AWS billing charges, which helps prevent cost surprises.

2fill in blank

medium

Complete the code to enable detailed billing reports for DynamoDB.

DynamoDB

aws ce enable-cost-allocation-tags --tag-keys [1]

Drag options to blanks, or click blank then click option'

AEnvironment

BCostCenter

CProject

DService

Attempts:

3 left

💡 Hint

Common Mistakes

Selecting tags unrelated to cost management.

Confusing service tags with cost allocation tags.

Enabling the CostCenter tag helps allocate costs and manage budgets effectively.

3fill in blank

hard

Fix the error in the query to get DynamoDB cost data from AWS Cost Explorer.

DynamoDB

aws ce get-cost-and-usage --time-period Start=2023-01-01,End=2023-01-31 --granularity MONTHLY --metrics [1] --filter '{"Dimensions":{"Key":"SERVICE","Values":["DynamoDB"]}}'

Drag options to blanks, or click blank then click option'

AUnblendedCost

BBlendedCost

CUsageQuantity

DTotalCost

Attempts:

3 left

💡 Hint

Common Mistakes

Using UsageQuantity which shows usage, not cost.

Choosing TotalCost which is not a valid metric.

The UnblendedCost metric provides the actual cost without blending, which is accurate for cost management.

4fill in blank

hard

Fill both blanks to create a budget alert for DynamoDB costs exceeding $500.

DynamoDB

aws budgets create-budget --account-id 123456789012 --budget '{"BudgetName": "DynamoDBCostBudget", "BudgetLimit": {"Amount": "[1]", "Unit": "USD"}, "TimeUnit": "MONTHLY", "BudgetType": "[2]"}'

Drag options to blanks, or click blank then click option'

A500

B1000

CCOST

DUSAGE

Attempts:

3 left

💡 Hint

Common Mistakes

Setting the budget type to USAGE instead of COST.

Using an incorrect amount value.

The budget limit is set to 500 USD and the budget type is COST to track spending.

5fill in blank

hard

Fill all three blanks to filter DynamoDB cost data by linked account and service.

DynamoDB

aws ce get-cost-and-usage --time-period Start=2023-05-01,End=2023-05-31 --granularity DAILY --metrics [1] --filter '{"And":[{"Dimensions":{"Key":"[2]","Values":["[3]"]}},{"Dimensions":{"Key":"SERVICE","Values":["Amazon DynamoDB"]}}]}'

Drag options to blanks, or click blank then click option'

AUnblendedCost

BLINKED_ACCOUNT

C123456789012

DUsageQuantity

Attempts:

3 left

💡 Hint

Common Mistakes

Using UsageQuantity instead of a cost metric.

Using SERVICE as the filter key for account ID.

The metric UnblendedCost shows actual cost. The filter uses LINKED_ACCOUNT key with the account ID 123456789012 to narrow down costs.

Practice

1. Why is cost management important when using DynamoDB?

easy

A. It automatically increases your database capacity.

B. It helps avoid unexpected high bills by monitoring usage.

C. It guarantees 100% uptime for your database.

D. It encrypts your data for security.

Solution

1. Step 1: Understand the purpose of cost management

   Cost management is about tracking and controlling how much you spend.

2. Step 2: Relate cost management to DynamoDB usage

   By monitoring usage, you can avoid surprises in your bill.

3. Final Answer:

   It helps avoid unexpected high bills by monitoring usage. -> Option B

4. Quick Check:

   Cost management = Avoid surprises [OK]

Hint: Cost management = watch spending to avoid surprises [OK]

Common Mistakes:

• Thinking cost management changes capacity automatically
• Confusing cost management with security features
• Assuming cost management guarantees uptime

2. Which AWS tool can you use to set alerts for DynamoDB spending?

easy

A. AWS Cost Explorer

B. AWS Lambda

C. AWS Budgets

D. AWS CloudTrail

Solution

1. Step 1: Identify tools for cost alerts

   AWS Budgets lets you set spending limits and alerts.

2. Step 2: Differentiate from other AWS tools

   Cost Explorer shows reports, Lambda runs code, CloudTrail logs events.

3. Final Answer:

   AWS Budgets -> Option C

4. Quick Check:

   Alerts = AWS Budgets [OK]

Hint: Set alerts with AWS Budgets, not Cost Explorer [OK]

Common Mistakes:

• Confusing Cost Explorer with alert setting
• Choosing Lambda which is for running code
• Picking CloudTrail which logs API calls

3. You set a budget alert for $100 monthly on DynamoDB usage. Your usage hits $120. What happens?

medium

A. Nothing happens; alerts only work after $150.

B. Your DynamoDB service stops automatically.

C. AWS refunds the extra $20 automatically.

D. You get an alert notifying you exceeded $100.

Solution

1. Step 1: Understand budget alert behavior

   Budget alerts notify you when spending exceeds the set limit.

2. Step 2: Check consequences of exceeding budget

   Alerts do not stop service or refund money automatically.

3. Final Answer:

   You get an alert notifying you exceeded $100. -> Option D

4. Quick Check:

   Budget alert triggers notification [OK]

Hint: Budget alert = notification, not service stop [OK]

Common Mistakes:

• Thinking service stops automatically
• Expecting automatic refunds
• Believing alerts only trigger after higher limits

4. You wrote this alert rule but never got notified despite high usage:

{
  "BudgetLimit": 50,
  "Notification": {
    "Threshold": 80,
    "Type": "ACTUAL"
  }
}

What is the likely error?

medium

A. Missing alert email address configuration.

B. Threshold should be a percentage, not a number.

C. Notification type "ACTUAL" is invalid.

D. BudgetLimit must be in cents, not dollars.

Solution

1. Step 1: Analyze the provided alert rule JSON

   The snippet includes BudgetLimit, Threshold (80% correctly as number), and ACTUAL type, but omits Subscribers configuration.

2. Step 2: Recall AWS Budgets notification requirements

   Notifications require specifying recipients like email or SNS topics; without them, no alerts are sent even if thresholds are met.

3. Final Answer:

   Missing alert email address configuration. -> Option A

4. Quick Check:

   Missing subscribers = no notification [OK]

Hint: Budget notifications require email/SNS subscriber config [OK]

Common Mistakes:

• Misinterpreting threshold 80 as wrong (it's correct for 80%)
• Thinking BudgetLimit must be in cents (it's dollars)
• Believing "ACTUAL" notification type is invalid

5. You want to avoid surprise costs by combining DynamoDB cost monitoring and automatic scaling. Which approach helps best?

hard

A. Use AWS Budgets with alerts and enable DynamoDB Auto Scaling to adjust capacity.

B. Only use DynamoDB Auto Scaling; budgets are unnecessary.

C. Set a fixed high capacity to avoid throttling and ignore budgets.

D. Manually check usage monthly without alerts or scaling.

Solution

1. Step 1: Combine cost monitoring and capacity management

   AWS Budgets alerts you about spending; Auto Scaling adjusts capacity to demand.

2. Step 2: Evaluate other options

   Only Auto Scaling misses cost alerts; fixed capacity wastes money; manual checks risk surprises.

3. Final Answer:

   Use AWS Budgets with alerts and enable DynamoDB Auto Scaling to adjust capacity. -> Option A

4. Quick Check:

   Budgets + Auto Scaling = best cost control [OK]

Hint: Combine budgets alerts with auto scaling for best cost control [OK]

Common Mistakes:

• Relying only on auto scaling without cost alerts
• Setting fixed capacity wastes money
• Ignoring alerts and manual checks cause surprises