A load balancer distributes incoming requests across multiple servers using strategies like round robin, weighted round robin, hash, and least connections, with health checks and a fronting ip.

Learn how in-memory databases store data in RAM for ultra low latency, use disk-backed transaction logs to protect data, and scale with distributed clusters and in-sync replicas to improve robustness.

Show how relational databases prioritize consistency and availability over partition tolerance under ACID, using master–slave replication, and contrast with non-relational databases that tolerate partitioning at the expense of consistency.

Compare soap, rest, and the query language that reduces overfetching, noting xml verbosity, endpoint driven requests, and client defined attributes.

Differentiate synchronous and asynchronous calls: synchronous blocks the main thread until a response, while asynchronous spawns a new thread so the main thread continues, as in checkout and printing invoices.

Http, as an application protocol, relies on transport layer protocols. Tcp provides connection-oriented reliability with in-order delivery, while udp trades reliability for speed.