AWS ElastiCache Scenario based questions ❓

❓Your web application is experiencing slow performance during peak times. How would you use ElastiCache with Memcached to improve performance?

Answer: Add additional Memcached nodes to distribute the load and enable horizontal scaling. Use client-side sharding to distribute data evenly across nodes.

❓You have a critical application that requires high availability and quick recovery from node failures. How would you configure ElastiCache for Redis to meet this requirement?

Answer: Configure Redis in Multi-AZ mode with automatic failover. Set up read replicas in different Availability Zones to ensure high availability and data durability.

❓Your application needs to ensure that cached data is always up-to-date. Which caching strategy would you use with ElastiCache?

Answer: Use a Write-Through caching strategy to ensure that every write operation updates both the cache and the underlying data store.

❓Users are experiencing high latency when accessing frequently requested data. How can ElastiCache help reduce latency?

Answer: Use ElastiCache to cache frequently accessed data, reducing the need to query the underlying database and thereby reducing latency.

❓How would you handle cache invalidation in ElastiCache when the underlying data changes?

Answer: Implement a cache invalidation strategy such as setting an appropriate TTL (Time to Live) for cache entries or using a cache-aside pattern where the application invalidates the cache entry when data is updated.

❓Your global application requires low-latency data access across multiple regions. How would you configure ElastiCache to achieve this?

Answer: Use Global Datastore for Redis to replicate data across multiple AWS regions, ensuring low-latency access for users worldwide.

❓How would you use ElastiCache to manage user sessions in a stateless web application?

Answer: Store session data in ElastiCache (either Redis or Memcached) to enable quick retrieval and management of session information across multiple instances of the web application.

❓What strategy would you implement to handle cache misses in your application?

Answer: Implement a lazy loading (cache-aside) strategy where the application fetches data from the underlying data store and stores it in the cache upon a cache miss.

❓Your application needs to cache large objects. Which ElastiCache engine would you choose and why?

Answer: Choose Redis, as it supports complex data structures and can handle large objects more efficiently than Memcached.

❓How can you ensure that your Redis nodes automatically failover in case of a primary node failure?

Answer: Configure ElastiCache for Redis in Multi-AZ mode with automatic failover. This ensures that a read replica is promoted to primary in case of a failure.

❓What ElastiCache metrics would you monitor to ensure the health and performance of your cache nodes?

Answer: Monitor metrics such as CPU utilization, memory usage, eviction count, read/write operations, and replication lag to ensure the health and performance of ElastiCache nodes.

❓How would you ensure data durability in Redis with ElastiCache?

Answer: Enable Redis persistence by configuring RDB snapshots or AOF (Append-Only File) logs to ensure data durability.

❓How would you secure your ElastiCache nodes in a production environment?

Answer: Use VPCs to isolate ElastiCache nodes, enable encryption in transit and at rest, use IAM policies for access control, and restrict access using security groups.

❓Your application requires a warm cache before going live. How would you prepopulate the ElastiCache?

Answer: Implement a cache warm-up strategy by preloading the cache with frequently accessed data before the application goes live, either manually or via a script.

❓How would you optimize costs when using ElastiCache for a variable workload?

Answer: Use Auto Scaling to dynamically adjust the number of cache nodes based on demand, choose the appropriate instance types, and optimize your cache key management to minimize unnecessary data storage.

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