Which service makes it easy to set up, manage, and scale distributed in-memory cache environments in the AWS Cloud?

• A. Amazon DynamoDB
• B. Amazon ElastiCache
• C. Amazon RDS
• D. Amazon Neptune

Answer: (B)

The key idea is a fully managed in-memory caching service that lets you run Redis or Memcached clusters and scale them easily. ElastiCache provides exactly that: a service you can provision to create distributed caches, with automated patching, backups, monitoring, and the ability to add or remove nodes or shards as your workload grows. Storing hot data in memory dramatically lowers latency and ElastiCache makes this scalable by supporting cluster mode (for Redis) and multiple nodes, along with high availability features like automatic failover. You can also secure access through VPCs and encryption, making it suitable for production workloads.

DynamoDB is a database, not a general-purpose cache (though it can be accelerated with DAX, which is a different offering). RDS is a relational database service, and Neptune is a graph database. None of these centers on providing a managed distributed in-memory cache environment in the same way ElastiCache does.