CS System Architecture & Design 3

Question 1

A video streaming service wants to reduce latency for users worldwide by serving static content from servers geographically close to them. Which technology accomplishes this?

Accepted Answer

A content delivery network (CDN)

Answer

A CDN caches static content at edge locations near users, cutting round-trip latency.

Question 2

Which database technique splits a large table's rows across multiple servers based on a key, such as user ID?

Accepted Answer

Sharding (horizontal partitioning)

Answer

Sharding distributes rows across servers by a partition key so each server holds a subset of the data.

Question 3

In a microservices system, an API gateway primarily serves to:

Accepted Answer

Provide a single entry point that routes requests to backend services

Answer

An API gateway is the unified front door that routes, authenticates, and often rate-limits requests to services.

Question 4

A payment service occasionally receives the same request twice due to network retries. What property should the API be designed with so duplicate requests do not double-charge customers?

Accepted Answer

Idempotency

Answer

An idempotent operation produces the same result no matter how many times it is repeated.

Question 5

Which pattern prevents a failing downstream service from exhausting resources by temporarily blocking calls to it after repeated failures?

Accepted Answer

Circuit breaker

Answer

A circuit breaker trips after repeated failures and short-circuits further calls until the service recovers.

(CS) Computer Science Practice Test

(CS) Computer Science Practice Test

CS System Architecture & Design 3