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REST Interview Questions & Answers- Part 7
Landing a job at a product-based company? Expect to be tested deeply on REST API fundamentals. These companies often deal with large-scale applications that require robust, secure, and scalable APIs to support millions of users. Interviewers will ask you about API lifecycle management, request optimization, throttling, and version control.
This page compiles essential REST API interview questions that reflect the kind of system-level thinking required at top tech firms. Whether you’re interviewing for a backend, DevOps, or full stack role, you’ll find value in reviewing topics like statelessness, API documentation (Swagger/OpenAPI), response caching, and JWT-based authentication. Understanding how REST APIs support user interactions, data syncing, and platform integrations will help you explain your solutions clearly.
Use this guide to not only answer questions but also to show that you understand the big picture. With proper prep, you’ll stand out in interviews at companies building large, reliable digital products.
Answer:
RESTful web services offer several advantages, including:
- Support for various data formats, such as JSON and XML.
- Compatibility with web browsers and easy integration into web applications.
- Efficient use of bandwidth, particularly with JSON-based APIs.
- Accessibility to developers with various programming languages.
- The ability to leverage existing models and resources.
- Simplicity and scalability, making them ideal for modern web and mobile applications.
Answer:
A successful request is indicated by an HTTP status code falling within the range of 200 to 299. The response body contains the requested resource or indicates success, allowing the client to use the response for further processing. In this case, the request was successful and completed its intended operation. Conversely, a failed request is signaled by an HTTP status code falling outside the range of 200 to 299, with the response body containing an error message explaining the failure. The client cannot use the response for further processing, and the request was not successful, failing to complete its intended operation.
Answer:
Pagination in RESTful web services involves breaking down a large dataset into smaller, manageable portions or pages. Clients can request data in these smaller chunks, rather than retrieving the entire dataset at once. Pagination helps reduce data transfer and improves performance, especially when dealing with extensive datasets.
Answer:
CORS (Cross-Origin Resource Sharing) is a security mechanism that allows web browsers to make cross-origin HTTP requests, facilitating resource sharing between different domains. It is a security feature that ensures controlled cross-origin access.
CSRF (Cross-Site Request Forgery), on the other hand, is a security vulnerability that involves tricking a user into unknowingly performing actions on a web application without their consent. CSRF attacks exploit the user’s active session on a website to perform unauthorized actions.
Answer:
DELETE is employed to delete specific rows from a table and is considered a Data Manipulation Language (DML) command. It may use a WHERE clause to specify which rows to delete, locks and logs individual row deletions, but is slower compared to TRUNCATE for large data sets. DELETE deletes rows one at a time and records each deletion in the transaction log. It does not reset identity column values, can be used with indexed views, may activate triggers, and consumes more transaction space than TRUNCATE.
On the contrary, TRUNCATE is used to remove all rows from a table and is a Data Definition Language (DDL) command. It does not support a WHERE clause and removes all rows, locks and logs page deallocations for the entire table, making it faster than DELETE for large data sets. TRUNCATE deallocates data pages, with only page deallocations logged in the transaction log. It resets identity column values to their seed value, cannot be used with indexed views, does not activate triggers, and consumes less transaction space than DELETE.
Answer:
Logging in RESTful web services can be implemented using various logging frameworks and libraries, such as log4j, Logback, or SLF4J. These frameworks allow developers to capture important events, errors, performance metrics, and request/response data. Logging can be configured to write log messages to different destinations like files, consoles, or remote servers. It plays a crucial role in monitoring and debugging applications.
Answer:
A stateless API operates with the server not retaining session information between requests, making each request independent and self-contained. Clients must include all required information in each request, simplifying scaling as no session information needs to be managed. In contrast, a stateful API maintains session information between requests, with each request depending on the state of previous requests. Clients may not need to include all required information in each request, but scaling can be more challenging due to the need to maintain session state.
Answer:
Tracing in RESTful web services involves tracking the journey of a request as it traverses through various components of a distributed system. It is used for diagnosing performance and functional issues within the system. Tracing frameworks and libraries like OpenTelemetry, Zipkin, and Jaeger are employed to capture key information such as request IDs, service names, timestamps, and request/response data to gain insights into the flow and performance of requests.
Answer:
Implementing tracing in RESTful web services entails the inclusion of a unique identifier, known as a trace ID, in each request as it traverses through the various components of the system. This trace ID enables developers to monitor the path of a request within the system, facilitating the identification of potential issues or bottlenecks. To implement tracing, developers can leverage tools like OpenTracing or Zipkin, which provide APIs for generating and propagating trace IDs.
Answer:
Observability refers to the capacity to comprehend and monitor a system’s behavior from an external perspective. Within the realm of RESTful web services, observability involves the collection and analysis of data related to requests, responses, and various metrics. This data offers insights into the system’s performance, encompassing aspects such as response times, error rates, and resource utilization. Observability plays a pivotal role in ensuring the reliability and availability of RESTful web services.
Answer:
To implement observability in RESTful web services, developers can employ tools such as monitoring and logging frameworks, which provide visibility into system performance and behavior. These tools are capable of capturing data pertaining to requests, responses, and various metrics. Subsequently, this data can be analyzed and visualized using tools like Grafana or Kibana. Additionally, developers can harness distributed tracing frameworks like Jaeger or Zipkin to gain insights into how requests are handled across multiple services.
Answer:
In the context of RESTful web services:
- Synchronous communication involves a client sending a request to a server and waiting for a response before proceeding further.
- Asynchronous communication, conversely, entails a client sending a request to a server but continuing with other tasks while awaiting a response.
Asynchronous communication is commonly employed in RESTful web services for operations that are long-running or resource-intensive, as it mitigates the need for clients to endure prolonged wait times.
Question 133: What is the contrast between versioning an API via URI and via media type in REST API?
Answer:
When it comes to versioning an API in REST:
- Versioning via URI involves including the version number directly in the URI, such as “/api/v1/users.”
- Versioning via media type incorporates the version number within the media type, for example, “application/vnd.company.v1+json.”
Key distinctions include the fact that URI versioning alters the URI with each version, potentially causing caching and bookmark-related issues, and it can clutter the URI with version numbers. In contrast, media type versioning maintains a consistent URI while indicating the version within the media type, albeit potentially resulting in lengthy media type designations.
Answer:
To facilitate asynchronous communication in RESTful web services, developers can employ various techniques. These include the utilization of message queues, which enable clients to dispatch requests to a server and receive responses at a later time. Additionally, frameworks like ReactiveX or Spring WebFlux can be adopted, as they provide support for asynchronous programming models.
Answer:
RESTful web services predominantly employ JSON (JavaScript Object Notation) as the prevailing message format. JSON is favored for its lightweight, text-based nature, making it easily readable and parseable. While JSON is the primary choice, other formats like XML and YAML are occasionally used, albeit less frequently.
Answer:
Message brokers serve as middleware components that enable the transmission and reception of messages between disparate systems or services. In the context of RESTful web services, message brokers play a pivotal role in facilitating asynchronous communication. Here’s how they function: a client sends a request to a message broker, which subsequently routes the request to the appropriate service. Prominent message brokers employed in RESTful web services include Apache Kafka and RabbitMQ.
Answer:
RESTful web services and microservices represent distinct architectural styles for building distributed systems. Notable distinctions include:
- RESTful web services focus on exposing resources over HTTP using a standardized set of operations (GET, POST, PUT, DELETE).
- Microservices prioritize the creation of small, loosely coupled services that can be independently developed and deployed.
Answer:
Containerization involves the bundling of an application and its dependencies into a container, which can be deployed on infrastructure supporting containerization. Containers create a self-contained and transportable runtime environment, isolating the application from the host infrastructure. RESTful web services can be placed within containers and then deployed on container platforms like Docker and Kubernetes. Containerization streamlines the deployment, scaling, and administration of RESTful web services by providing a lightweight and adaptable environment.
Answer:
RESTful web services and GraphQL are both employed for constructing APIs for web applications, yet they differ fundamentally in their approach. The primary contrast lies in the way they handle data retrieval:
- RESTful APIs rely on a fixed set of endpoints and predefined data structures. Clients interact with these endpoints to access data.
- GraphQL, on the other hand, empowers clients to request specific data structures, permitting them to obtain precisely the data they require. This flexibility makes GraphQL well-suited for complex use cases where clients necessitate precise control over their data retrieval process.
Answer:
Webhooks are a mechanism employed by RESTful web services to notify clients of events occurring on the server. When a pertinent event transpires, the server dispatches an HTTP request to a URL specified by the client. This real-time notification process allows clients to receive updates without the need for continuous polling of the server, enhancing efficiency and responsiveness.