Back-End Development Cheat Sheet 2026

The 30 highest-yield Back-End Development facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. In the context of full-stack development, what is a 'middleware' function? → A function that executes between receiving a request and sending a response
2. What is the purpose of a reverse proxy like Nginx in a back-end setup? → Sitting in front of application servers to handle routing, SSL, and load balancing
3. Which of the following is a constraint of REST architecture? → Statelessness
4. Which HTTP header is used to prevent clickjacking attacks on web back-ends? → X-Frame-Options
5. Which SQL statement correctly adds a foreign key constraint to an existing table? → ALTER TABLE orders ADD FOREIGN KEY (customer_id) REFERENCES customers(id);
6. Which algorithm is commonly used for consistent hashing in distributed caching systems? → Ring-based consistent hashing
7. Which technique prevents SQL injection attacks in back-end code? → Using parameterized queries or prepared statements
8. What is HTTP caching and which header controls cache duration for browser and CDN caching? → Browser and CDN caching of HTTP responses — controlled by the Cache-Control header
9. A word or phrase used to specify which columns should be returned by a query → Select
10. Which of the following is a key advantage of using environment variables for configuration? → They keep sensitive data out of source code
11. What does ACID stand for in database transactions? → Atomicity, Consistency, Isolation, Durability
12. A broad view of a database showing all its tables and connections. → Schema
13. What does 'idempotency' mean in the context of a message consumer? → Processing the same message multiple times produces the same result as processing it once
14. What is the purpose of message durability in a message broker? → Ensuring messages survive broker restarts by persisting them to disk
15. In a microservices architecture, what is service discovery used for? → Allowing services to dynamically find the network location of other services
16. What is the purpose of database sharding in large-scale back-end systems? → To horizontally partition data across multiple database instances to improve scalability
17. In GraphQL, what is the purpose of a resolver function? → To fetch or compute the data for a specific field in a query
18. A set of data spanning all rows in a table with the same datatype (records) → Column
19. What HTTP status code should a REST API return when a resource is successfully created? → 201 Created
20. What is the best way to prevent SQL injection in a back-end application? → Using parameterized queries or prepared statements
21. In REST API design, what is the correct URL pattern for retrieving a specific user by ID? → /users/5
22. Which SQL function returns the number of rows in a group, including rows with NULL values? → COUNT(*)
23. What does the term 'API endpoint' refer to in back-end development? → A specific URL that accepts requests and returns data
24. In a typical MVC back-end architecture, what is the role of the Controller? → Handles incoming requests and coordinates Model and View
25. What is 'event sourcing' in back-end architecture? → Storing all state changes as an ordered, immutable sequence of events
26. What is JWT and what is it commonly used for in back-end applications? → JSON Web Token — used for stateless authentication and authorization
27. What is the difference between authentication and authorization? → Authentication verifies identity; authorization determines permissions
28. What does eventual consistency mean in a distributed back-end system? → Given enough time without new writes, all nodes will converge to the same value
29. What is the purpose of environment variables in back-end application security? → To store sensitive configuration like API keys and passwords outside of source code
30. In the context of back-end APIs, what is rate limiting? → Restricting the number of requests a client can make in a given time period