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

A relational database for storing structured data

Answer

A front-end state management library

Answer

A cloud object storage service

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 operations wait for network or disk; I/O-bound operations require heavy computation

Answer

CPU-bound operations run on the server; I/O-bound operations run on the client

Answer

There is no meaningful difference in back-end performance tuning

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

Loading all data at startup to avoid delays later

Answer

Caching data indefinitely to avoid repeated database queries

Answer

Loading data in alphabetical order for efficiency

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

The total time a server has been running

Answer

The maximum time a database query is allowed to run

Answer

The time limit for an API request to complete

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

Resizing images for mobile devices — JPEG compression

Answer

Encrypting response payloads — AES compression

Answer

Minifying JavaScript files — UglifyJS compression

Question 6

What is the purpose of a worker process or background job in a back-end application?

Accepted Answer

To handle time-consuming tasks (email sending, image processing, report generation) asynchronously outside the request-response cycle

Answer

To replace the main web server process for heavy traffic

Answer

To monitor the health of the web server process

Answer

To synchronize database replicas in real time