GraphQL Quiz - MCQ - Multiple Choice Questions

GraphQL is a query language for APIs and a runtime for executing those queries by using a type system you define for your data. It allows clients to request exactly the data they need and nothing more, making it efficient for modern web applications.

This quiz will test your basic understanding of GraphQL, its structure, and how it works. Each question includes an explanation to help you better understand the concepts.

Let’s begin with these multiple-choice questions (MCQs) to test your knowledge of GraphQL.

1. What is GraphQL?

a) A database management system

b) A query language for APIs

c) A programming language

d) A front-end framework

Answer:

b) A query language for APIs

Explanation:

GraphQL is a query language that allows clients to request specific data from APIs, and it executes those queries using a defined type system.

2. Who developed GraphQL?

a) Google

b) Microsoft

c) Facebook

d) Amazon

Answer:

c) Facebook

Explanation:

GraphQL was developed by Facebook in 2012 to improve the performance and flexibility of its mobile applications.

3. Which of the following is a feature of GraphQL?

a) Strongly typed schema

b) Only allows fixed queries

c) No support for real-time updates

d) GraphQL is only used for front-end development

Answer:

a) Strongly typed schema

Explanation:

GraphQL uses a strongly typed schema to define the API's structure, making it easy to understand what data can be queried and how.

4. In GraphQL, how does the client request data?

a) By using RESTful endpoints

b) By sending SQL queries

c) By sending GraphQL queries to a single endpoint

d) By using SOAP protocol

Answer:

c) By sending GraphQL queries to a single endpoint

Explanation:

GraphQL allows clients to send queries to a single endpoint, unlike REST, which requires different endpoints for different types of requests.

5. What is a key advantage of GraphQL over REST?

a) You can only send POST requests

b) GraphQL fetches exactly the data you need

c) GraphQL requires multiple endpoints

d) GraphQL is slower than REST

Answer:

b) GraphQL fetches exactly the data you need

Explanation:

One of the main advantages of GraphQL over REST is that it allows clients to request only the data they need, avoiding over-fetching or under-fetching data.

6. What does the root type "Query" represent in GraphQL?

a) It defines the write operations in GraphQL

b) It represents the read operations to fetch data

c) It is used for real-time subscriptions

d) It handles error responses

Answer:

b) It represents the read operations to fetch data

Explanation:

The "Query" root type in GraphQL is used to fetch data (read operations) from the server.

7. What does "mutation" in GraphQL refer to?

a) An error handling mechanism

b) A type of query to read data

c) A way to modify data (create, update, delete)

d) A performance improvement technique

Answer:

c) A way to modify data (create, update, delete)

Explanation:

Mutations in GraphQL are used to modify data, such as creating, updating, or deleting records.

8. Which of the following is a valid GraphQL data type?

a) INT

b) BOOL

c) Float

d) StringArray

Answer:

c) Float

Explanation:

GraphQL has a set of built-in scalar types, including Float for floating-point numbers, as well as other types like String, Int, and Boolean.

9. What is a GraphQL schema?

a) A database design diagram

b) A type system that defines the structure of data that can be queried

c) A front-end framework

d) A set of CSS rules

Answer:

b) A type system that defines the structure of data that can be queried

Explanation:

A GraphQL schema defines the types, queries, and mutations that are allowed, forming the contract between the client and server.

10. Which of the following is used for real-time communication in GraphQL?

a) Queries

b) Mutations

c) Subscriptions

d) Polling

Answer:

c) Subscriptions

Explanation:

Subscriptions in GraphQL are used for real-time updates, allowing clients to receive data whenever certain events happen on the server.

11. How does GraphQL handle errors?

a) It returns HTTP error codes

b) It returns all errors in the "errors" field of the response

c) It stops the execution of the query

d) It retries the query automatically

Answer:

b) It returns all errors in the "errors" field of the response

Explanation:

GraphQL handles errors by returning them in the "errors" field of the response, along with any partial data that was successfully fetched.

12. In GraphQL, which query allows the client to specify exactly which fields it wants?

a) REST query

b) Precise query

c) Explicit query

d) GraphQL query

Answer:

d) GraphQL query

Explanation:

In GraphQL, a query allows clients to request exactly the fields they need, making data fetching efficient and flexible.

13. Can GraphQL be used alongside REST APIs?

a) No, they are mutually exclusive

b) Yes, GraphQL can be used with REST APIs

c) Only in certain cases

d) GraphQL must replace REST APIs

Answer:

b) Yes, GraphQL can be used with REST APIs

Explanation:

GraphQL can work alongside REST APIs, and many applications use both technologies during transitions or to serve different types of requests.

14. How does GraphQL improve over-fetching and under-fetching issues common in REST?

a) By sending multiple API requests

b) By allowing the client to request only the specific data it needs

c) By caching the entire response

d) By using SOAP for data fetching

Answer:

b) By allowing the client to request only the specific data it needs

Explanation:

GraphQL solves over-fetching and under-fetching issues by allowing clients to request exactly the data they need, avoiding unnecessary data transfer.

15. What is the format of a GraphQL response?

a) XML

b) JSON

c) Plain text

d) YAML

Answer:

b) JSON

Explanation:

GraphQL responses are returned in JSON format, which includes both the data requested and any errors encountered during execution.

16. In a GraphQL schema, what does the "!" symbol represent?

a) The field is required

b) The field is an array

c) The field has a default value

d) The field is deprecated

Answer:

a) The field is required

Explanation:

The "!" symbol in a GraphQL schema indicates that the field is non-nullable, meaning the client must receive a value for that field.

17. Can GraphQL be used for a microservices architecture?

a) No, GraphQL is not compatible with microservices

b) Yes, it can act as a gateway for multiple microservices

c) Only for authentication services

d) Only for small applications

Answer:

b) Yes, it can act as a gateway for multiple microservices

Explanation:

GraphQL can be used as a gateway to aggregate data from multiple microservices, providing a single entry point for client requests.

18. In GraphQL, what does "field resolver" refer to?

a) A function that resolves the value for a field

b) A tool for debugging queries

c) A method to define data types

d) A way to format error responses

Answer:

a) A function that resolves the value for a field

Explanation:

In GraphQL, a field resolver is a function that returns the value for a particular field in the query, typically by fetching data from a database or another service.

19. What is "Apollo" in the context of GraphQL?

a) A GraphQL schema definition

b) A library for building GraphQL APIs and clients

c) A front-end framework

d) A JavaScript testing tool

Answer:

b) A library for building GraphQL APIs and clients

Explanation:

Apollo is a popular library for building GraphQL APIs and clients. It makes it easier to integrate GraphQL with web and mobile applications.

20. In a GraphQL query, how do you request data from nested objects?

a) By creating a separate query for each object

b) By sending a POST request

c) By specifying fields inside the nested objects in the query

d) By using multiple endpoints

Answer:

c) By specifying fields inside the nested objects in the query

Explanation:

In GraphQL, you can request data from nested objects by specifying the fields inside those objects directly in the query, retrieving hierarchical data in a single request.

21. What does "introspection" mean in GraphQL?

a) A way to inspect the schema and its types

b) A performance optimization method

c) A query to modify the schema

d) A method to format responses

Answer:

a) A way to inspect the schema and its types

Explanation:

GraphQL introspection allows clients to query information about the schema itself, such as available types and fields, making it easier to understand and explore APIs.

22. What is "fragments" used for in GraphQL?

a) To split large queries into smaller ones

b) To reuse sets of fields in multiple queries

c) To cache query results

d) To paginate results

Answer:

b) To reuse sets of fields in multiple queries

Explanation:

Fragments in GraphQL are used to reuse sets of fields in multiple queries, making the queries more concise and maintainable.

23. What is the default HTTP method used to send GraphQL queries?

a) GET

b) POST

c) PUT

d) DELETE

Answer:

b) POST

Explanation:

GraphQL queries are typically sent to the server using the HTTP POST method, though some servers also support GET for certain types of queries.

24. How can you combine multiple operations into one GraphQL query?

a) Using variables

b) Using fragments

c) Using aliases

d) Using unions

Answer:

c) Using aliases

Explanation:

In GraphQL, aliases allow you to combine multiple operations in one query by assigning different names to the results, even if the operations use the same fields or types.

25. What is a "non-nullable" type in GraphQL?

a) A field that must always return a value

b) A field that can have any value, including null

c) A deprecated field

d) A field used for pagination

Answer:

a) A field that must always return a value

Explanation:

A non-nullable type in GraphQL ensures that the field must always return a value and cannot be null, improving reliability.

These questions cover the fundamental concepts of GraphQL, including its syntax, usage, and common features. Understanding these basics will help you build more efficient APIs and better query data for modern web applications.