Back-End Development Back-End Performance and Caching

Question 1

What is Redis and what is it commonly used for in back-end applications?

Accepted Answer

An in-memory data store used for caching, session management, real-time leaderboards, and message brokering

Answer

Redis is an in-memory key-value store with data structures like strings, hashes, lists, and sets, widely used to cache expensive computations, store sessions, and power real-time features.

Question 2

What is the difference between CPU-bound and I/O-bound operations in back-end applications?

Accepted Answer

CPU-bound operations are limited by processing power; I/O-bound operations are limited by waiting for external resources like disk or network

Answer

CPU-bound tasks (encryption, image processing) are bottlenecked by processor speed, while I/O-bound tasks (database queries, file reads) spend most time waiting for external systems.

Question 3

What is lazy loading in the context of back-end data retrieval?

Accepted Answer

Deferring the loading of data until it is actually needed, reducing initial load time and memory usage

Answer

Lazy loading delays fetching related data until it is explicitly accessed, avoiding unnecessary database queries and reducing memory consumption for data that may never be needed.

Question 4

What does TTL (Time to Live) mean in the context of caching?

Accepted Answer

The duration after which a cached item expires and must be refreshed from the source

Answer

TTL defines how long a cached value remains valid before it is considered stale and must be re-fetched or recomputed from the original data source.

Question 5

What is content compression and which algorithm is most commonly used for HTTP responses?

Accepted Answer

Reducing the size of HTTP response bodies — Gzip or Brotli compression

Answer

Gzip and Brotli compress HTTP response bodies (HTML, JSON, JS, CSS) before transmission, often reducing payload size by 60-80% and significantly improving transfer speeds.

Back-End Development Practice Test

Back-End Development Practice Test

Back-End Development Back-End Performance and Caching