Cache Invalidation Strategies Quiz: Understanding Concepts and Trade-offs Quiz

1. Understanding Cache Expiration Policies

   Which cache invalidation strategy relies on specifying a time-to-live (TTL) after which cached data is considered stale, regardless of data changes?

   1. Time-based expiration
   2. Client-invalidate pattern
   3. Adjecent cache update
   4. Write-through caching
   5. Eventual consistancy

2. Write-Through vs Write-Behind Caching

   In a write-behind cache strategy, when is data written to the underlying data store?

   1. Data is written asynchronously after being updated in cache
   2. Data is written immediately before updating the cache
   3. Data is never written to the data store
   4. Data is deleted from cache and main store at the same time
   5. Data is written only on cache miss

3. Cache Invalidation in Distributed Systems

   What is a major challenge of using a cache invalidation strategy in a distributed multi-node system?

   1. Ensuring all nodes receive invalidation notifications simultaneously
   2. Implementing least recently used (LRU) eviction
   3. Storing the entire dataset in memory
   4. Using strong encryption for cache data
   5. Avoiding frequent cache hits

4. Trade-offs with Manual Invalidation

   Which is a significant trade-off of using manual cache invalidation?

   1. Requires developers to accurately identify and clear stale cache entries
   2. Caches are always updated automatically
   3. Leads to increased disk I/O operations
   4. Reduces application runtime errors
   5. Forces cache expiration to zero

5. Understanding Cache Coherency

   Which phrase best defines cache coherency in the context of cache invalidation?

   1. Keeping cached data consistent with the original data source
   2. Ensuring the cache server has a large enough disk
   3. Running cache warmup scripts automatically
   4. Using only strong consistency models
   5. Periodic purging of the entire cache

6. Invalidation Using Event-based Notifications

   In which scenario would event-based invalidation be preferable over time-based expiration?

   1. When changes to the underlying data are unpredictable and need immediate reflection in cache
   2. When database reads far outnumber writes
   3. When cache size needs to be minimized
   4. When cache misses are not acceptable
   5. When cache eviction must be random

7. Potential Risks of Stale Data

   What is a potential drawback of using only time-based cache invalidation?

   1. Users may receive stale data before TTL has expired
   2. Data will always be served fresh from the database
   3. Increased risk of cache snowballing
   4. High CPU utilization on the cache server
   5. Cache misses will become impossible

8. Cache Busting Techniques

   What does cache busting generally refer to in web caching?

   1. Forcing the retrieval of new or updated data and ignoring the existing cache
   2. Increasing cache size
   3. Encrypting cached files
   4. Serving outdated resources to save bandwidth
   5. Reducing database availability

9. Using Cache Keys for Invalidation

   Given a scenario where product details may frequently change, how can cache key versioning assist in cache invalidation?

   1. By updating a version suffix on the key when data changes, forcing cache refresh
   2. By storing cache keys on disk
   3. By decreasing cache lookup speed
   4. By eliminating the need for a data store
   5. By increasing cache miss rates deliberately

10. Lazy Invalidation Pattern

    What is a key characteristic of the lazy invalidation cache pattern?

    1. Cache entries are checked for freshness only when accessed
    2. All cache entries are proactively cleared on every write
    3. Cache data is never removed automatically
    4. Database updates are rejected if cache is not updated
    5. Writes are only allowed after cache is empty