DVA-C02 exam dumps: questions 101 to 200 of 398

Correct answer: B

• A. Incorrect.

  Write-through caching is not suitable in this case because it writes data to the cache when the database is updated, but the scenario involves reading frequently requested data, not writing it.

• B. Correct.

  Read-through caching is the correct choice because it ensures that when data is requested, it is first checked in the cache, and if it's not there, it is fetched from the database and cached for subsequent requests. This reduces database load while keeping the cache updated with the latest data.

• C. Incorrect.

  Lazy loading caches data only when it is requested for the first time, but it does not guarantee that the cache always has the latest data. This could lead to stale data being served to users, which does not meet the requirement of always showing the most up-to-date product information.

• D. Incorrect.

  Time-to-live (TTL) caching is a mechanism to expire cached data after a specific duration, but it is not a standalone caching strategy. While TTL can complement a caching strategy, it does not address the need to ensure the cache always has the latest data.

Correct answer: A

• A. Correct.

  Write-through caching updates the cache immediately whenever the underlying database is updated, ensuring the cache remains consistent with the database and minimizing cache misses.

• B. Incorrect.

  Read-through caching loads data into the cache only when a cache miss occurs. This does not ensure immediate consistency between the cache and the database.

• C. Incorrect.

  Lazy loading loads data into the cache only when it is requested and not found in the cache. While it reduces unnecessary writes to the cache, it can result in higher cache miss rates and does not immediately reflect database updates in the cache.

• D. Incorrect.

  Time-to-live (TTL) is a mechanism to set an expiration time for cache entries. While it helps in controlling stale data, it is not a caching strategy by itself and does not ensure immediate consistency with the database.

Correct answer: A

• A. Correct.

  Write-through caching ensures that every write operation to the database is immediately written to the cache as well, keeping the cache in sync with the database. This is suitable for scenarios where data consistency is critical.

• B. Incorrect.

  Lazy loading caches the data only when it is requested and not found in the cache. While it reduces initial load on the cache, it doesn't ensure that the cache is always synchronized with the database.

• C. Incorrect.

  Read-through caching involves fetching data directly from the cache, and if the data is not in the cache, it is fetched from the database and then written to the cache. This does not directly handle synchronization during a write operation.

• D. Incorrect.

  Cache aside is a strategy where the application manages when to fetch and update the cache. It does not automatically synchronize the cache during database writes, which can lead to stale data in certain scenarios.

Correct answer: A

• A. Correct.

  Write-through caching ensures that whenever data is written to the database, it is also written to the cache simultaneously. This guarantees that the cache is always up-to-date, making it the most appropriate strategy in this scenario.

• B. Incorrect.

  Read-through caching is used to fetch data from the cache or the database when a read request is made. However, it does not ensure that the cache is updated when the database is updated, so this is not suitable for the given requirement.

• C. Incorrect.

  Lazy loading populates the cache only when a cache miss occurs. While it reduces initial cache overhead, it does not ensure that the cache is updated when DynamoDB data changes, which makes it unsuitable for this scenario.

• D. Incorrect.

  Cache-aside with time-to-live (TTL) allows data to expire after a set duration, requiring a database fetch on expiration. While it can reduce stale data, it does not guarantee immediate synchronization with DynamoDB upon updates.

Correct answers: B, D

• A. Incorrect.

  Incorrect: While transitioning to S3 Glacier Deep Archive is cost-effective, transitioning after 365 days does not match the requirement to delete the logs after 365 days.

• B. Correct.

  Correct: This rule transitions objects to the S3 Standard-IA class after 30 days for cost optimization and deletes them after 365 days, aligning perfectly with the requirements.

• C. Incorrect.

  Incorrect: Transitioning objects to S3 One Zone-IA is riskier as it stores data in a single Availability Zone, and transitioning to S3 Glacier after 365 days does not meet the requirement of deleting the logs after 365 days.

• D. Correct.

  Correct: Transitioning objects to S3 Intelligent-Tiering is a valid cost-optimization strategy for infrequent access, and expiring the objects after 365 days ensures the logs are deleted as required.

• E. Incorrect.

  Incorrect: Transitioning to S3 Glacier Deep Archive after 30 days is unnecessary for logs that are still frequently accessed during that period, and expiring them after 365 days is correct but not the most cost-effective solution for this use case.