Practice Test
True or False: In AWS, cache eviction is the process of removing old data from cache to accommodate new data.
- True
- False
Answer: True
Explanation: When cache is at capacity, AWS employs a method called cache eviction to remove older data or less frequently accessed data to make room for new data.
True or False: AWS Elasticache is a service that makes it easier to launch, operate, and scale popular NoSQL databases in the cloud.
- True
- False
Answer: False
Explanation: This is a description of Amazon DynamoDB. AWS Elasticache improves the performance of web applications by allowing you to retrieve information from fast, in-memory caches, instead of relying entirely on slower disk-based databases.
Which type of cache is designed to catch and store the most recently requested data?
- A. Write-through cache
- B. Write-back cache
- C. LRU (Least Recently Used) cache
- D. Most Recently Used cache
Answer: C. LRU (Least Recently Used) cache
Explanation: LRU (Least Recently Used) cache is designed to remove the least recently used items first. This technique is typically used to manage memory within the cache.
True or False: AWS ElastiCache supports Memcached and Redis.
- True
- False
Answer: True
Explanation: AWS ElastiCache is a web service that makes it easy to deploy and run Memcached or Redis protocol-compliant server nodes in the cloud.
Which of the following is NOT a caching strategy in AWS?
- A. Write-through caching
- B. Write-back caching
- C. Write-around caching
- D. Write-in caching
Answer: D. Write-in caching
Explanation: The common caching strategies used in AWS are Write-through caching, Write-back caching, and Write-around caching. There is no such strategy as Write-in caching.
True or False: A cache miss occurs when the requested data is not found in the cache memory.
- True
- False
Answer: True
Explanation: A cache miss is a state where data is not found in the cache memory, causing the system to fetch the data from the original storage location, which can cause delays.
Which caching strategy is best to use when writes are much more common than reads?
- A. Write-through caching
- B. Write-back caching
- C. Write-around caching
- D. Read-through caching
Answer: B. Write-back caching
Explanation: In write-back caching, data is only written to the cache and the write to the main memory is postponed until necessary. This results in fewer writes and less write latency.
True or False: In the caching strategy “Write-back cache”, data is written to main memory as soon as it changes in the cache.
- True
- False
Answer: False
Explanation: In “Write-back cache”, data is written to cache first and then it is written to main memory later when system is less busy or as per the need.
True or False: In a “Write-around cache”, misses do not fill the cache, resulting in reduced cache churn.
- True
- False
Answer: True
Explanation: In a “Write-around cache”, data is written directly to permanent storage, bypassing the cache. This can reduce the cache becoming cluttered with write-intense operations.
In AWS ElastiCache, which caching engine provides persistent storage?
- A. Memcached
- B. Redis
- C. Both A and B
- D. Neither A nor B
Answer: B. Redis
Explanation: Among the two caching engines supported by AWS ElastiCache, Redis supports highly available and persistent storage, whereas Memcached does not.
Interview Questions
What is a cache hit in AWS?
A cache hit occurs when the data requested by your application is available in the Elasticache node’s in-memory cache.
What do TTL (Time to Live) settings pertain to in AWS caching strategy?
TTL settings control how long the data is stored in a cache before it’s automatically removed or updated.
How does cache eviction work in AWS?
When cache space is needed, AWS uses an eviction policy (like least recently used, or LRU) to determine which items to remove from the cache.
In AWS, what is meant by write-through cache?
Write-through cache refers to a caching strategy where data is simultaneously written to the cache and the backing store to ensure consistency.
Why would you use a lazy-loading strategy in AWS caching?
A lazy-loading strategy only loads data into the cache when necessary, reducing unnecessary use of memory resources.
What is the benefit of using cache clustering in AWS?
Cache clustering allows for horizontal scalability. If the existing cache nodes are not sufficient, you can simply add more.
How does in-memory caching improve application performance in AWS?
In-memory caching stores data in the RAM, reducing reliance on slower disk-based databases. This can lead to substantial improvements in application performance.
For caching, what is the function of Amazon CloudFront?
Amazon CloudFront is a content delivery service that caches content at edge locations, reducing latency and delivering content more quickly to end users.
What is write-around cache in AWS?
Write-around cache is a strategy where data is written directly to the backing store, bypassing the cache. This can be beneficial if cached data is unlikely to be re-read in the near future.
What is the purpose of AWS’s caching service, ElastiCache?
AWS ElastiCache improves the performance of web applications by allowing you to retrieve information from an in-memory caching system, instead of slower disk-based databases.
What is cache partitioning in the context of AWS caching strategies?
Cache partitioning or sharding, involves splitting the total cache size into smaller, more manageable pieces each aimed at storing a subset of the data.
What is the use of a distributed cache in AWS?
A distributed cache in AWS is used to store copies of data across multiple nodes within a system. This aids in improving the speed by limiting the amount of work an individual node has to deal with.
What is the effect of overutilizing caching in AWS?
Overutilizing cache resources may lead to higher costs, potential cache thrashing due to high turnover of data, and increased memory usage which could degrade application performance.
How can caching improve database performance in AWS?
Caching can improve database performance by storing frequently accessed data closer to the application layer. As a result, subsequent requests for the data can be served from the cache, reducing the need for expensive and time-consuming database read operations.
What is the purpose of a cold cache in AWS?
A cold cache is a cache that doesn’t have the requested data when a request is made. The need to request this data from a slower, disk-based database can result in an initial performance hit, but it allows the cache to ‘warm up’—the data becomes subsequently available for faster retrieval from cache.
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