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Question 81:
Which HTTP status code indicates that a REST API request was successful and a new resource was created?
A) 200 OK
B) 201 Created
C) 202 Accepted
D) 204 No Content
Answer: B
Explanation:
This question addresses HTTP status codes, which are essential for understanding REST API responses and implementing proper error handling in applications. Developers must know which status codes indicate different response types to build robust API integrations.
Option B is correct because the 201 Created status code specifically indicates that a POST or PUT request successfully created a new resource on the server. When an API returns 201, it confirms the resource was created and typically includes a Location header containing the URI of the newly created resource, allowing clients to immediately access it. The response body often contains a representation of the created resource with its assigned identifier and other server-generated fields. This status code is semantically distinct from 200 OK, providing explicit confirmation that resource creation occurred rather than just successful processing.
Option A describes 200 OK, which indicates general request success but doesn’t specifically communicate that a new resource was created. While 200 could be returned for creation operations, 201 provides more precise semantics that improve API clarity and help clients understand exactly what happened.
Option C refers to 202 Accepted, which indicates the server accepted the request for processing but hasn’t completed it yet. This status is used for asynchronous operations where resource creation happens later, not for immediate synchronous creation.
Option D describes 204 No Content, which indicates successful processing without returning response body content. This status is typically used for DELETE operations or updates where no data needs to be returned, not for resource creation where clients usually need information about the created resource.
Understanding HTTP status codes enables developers to implement proper response handling, provide meaningful user feedback, distinguish between success types, debug API issues effectively, and build applications that correctly interpret server responses according to REST architectural principles.
Question 82:
What is the primary purpose of OAuth 2.0 in API security?
A) To provide delegated authorization allowing applications to access resources on behalf of users
B) To encrypt data transmitted between client and server
C) To authenticate users through username and password credentials
D) To prevent SQL injection attacks in database queries
Answer: A
Explanation:
This question examines OAuth 2.0, which is the industry-standard protocol for authorization that developers must understand when building secure applications that integrate with third-party services or implement API security.
Option A is correct because OAuth 2.0 provides delegated authorization, enabling applications to access protected resources on behalf of users without requiring users to share their credentials. OAuth separates authentication from authorization, allowing resource owners to grant limited access to their resources to third-party applications through access tokens. The protocol supports multiple flows (authorization code, implicit, client credentials, resource owner password) for different scenarios, with authorization code flow being most secure for web applications. OAuth tokens typically have limited scope and lifetime, reducing security risks if compromised. This delegation model enables scenarios like allowing a mobile app to access user’s cloud storage, granting a calendar application access to email contacts, or permitting analytics tools to read social media data without sharing passwords.
Option B describes encryption, which OAuth doesn’t provide directly. While OAuth requires HTTPS for secure token transmission, the protocol itself handles authorization rather than data encryption. Transport-layer security through TLS/SSL provides encryption independently of OAuth.
Option C refers to authentication, but OAuth is primarily an authorization protocol. While OAuth flows involve authentication, the protocol’s purpose is granting access permissions rather than verifying user identity. OpenID Connect builds on OAuth to provide authentication capabilities.
Option D mentions SQL injection prevention, which is unrelated to OAuth. SQL injection prevention requires input validation, parameterized queries, and secure coding practices rather than authorization protocols.
Developers implementing OAuth must understand authorization flows, token types, scope definitions, refresh token mechanisms, security best practices including PKCE for mobile applications, and proper token storage to build secure applications that protect user resources while enabling necessary third-party integrations.
Question 83:
In a microservices architecture, what is the primary function of an API gateway?
A) To provide a single entry point for routing requests to appropriate microservices and handling cross-cutting concerns
B) To store and manage all application data in a centralized database
C) To compile and deploy microservices to production environments
D) To monitor system performance and generate alerts for anomalies
Answer: A
Explanation:
This question addresses API gateways, which are critical components in microservices architectures that developers must understand when designing distributed systems. API gateways solve common challenges in managing multiple microservices.
Option A is correct because API gateways serve as single entry points for client requests, routing them to appropriate backend microservices based on request paths, methods, or headers. Gateways handle cross-cutting concerns that would otherwise require duplication across microservices, including authentication, authorization, rate limiting, request transformation, response aggregation, protocol translation, logging, and monitoring. By centralizing these concerns, gateways simplify microservice implementation, reduce code duplication, provide consistent security enforcement, enable easier service migration, and improve overall system maintainability. Gateways can aggregate responses from multiple microservices into single responses, reducing client complexity and network overhead. They also provide abstraction, allowing backend service changes without impacting clients.
Option B describes a centralized database, which contradicts microservices principles favoring distributed data management where each service owns its data. API gateways don’t manage application data but rather route requests to services that manage their own data.
Option C refers to deployment pipelines and CI/CD tools, which handle compilation and deployment processes. API gateways operate at runtime, routing requests rather than deploying services.
Option D mentions monitoring tools, which track system performance and generate alerts. While API gateways often include monitoring capabilities and integrate with observability platforms, their primary function is request routing and handling cross-cutting concerns rather than comprehensive system monitoring.
Developers should implement API gateways to simplify client interactions with microservices, enforce consistent security policies, manage rate limiting and throttling, enable service discovery integration, provide request/response transformation, aggregate data from multiple services, and centralize logging and monitoring for better observability across distributed architectures.
Question 84:
Which Python library is commonly used for making HTTP requests to REST APIs?
A) requests
B) flask
C) django
D) numpy
Answer: A
Explanation:
This question tests knowledge of Python libraries essential for API integration and development. Understanding which libraries serve specific purposes enables developers to choose appropriate tools for different tasks.
Option A is correct because the requests library is the standard Python library for making HTTP requests to REST APIs, web services, and web pages. The library provides simple, intuitive methods like requests.get(), requests.post(), requests.put(), and requests.delete() that correspond to HTTP methods. Requests handles authentication, headers, parameters, JSON encoding/decoding, file uploads, cookies, session management, and SSL verification automatically. The library’s elegant API makes HTTP operations straightforward with minimal code, supporting both simple requests and complex scenarios including custom headers, authentication schemes, timeout handling, and response streaming. Requests is widely adopted in the Python community and considered the de facto standard for HTTP client operations.
Option B describes Flask, which is a web framework for building web applications and APIs rather than consuming them. Flask creates HTTP servers that respond to requests rather than making outbound HTTP requests to other APIs.
Option C refers to Django, another web framework for building full-featured web applications. Like Flask, Django is used for creating web services rather than consuming external APIs, though applications built with Django often use the requests library to integrate with external services.
Option D mentions NumPy, which is a numerical computing library for array operations, mathematical functions, and scientific computing. NumPy has no relationship to HTTP requests or API consumption.
Developers using the requests library should understand proper error handling, timeout configuration, session reuse for multiple requests, authentication options including OAuth, proper use of params versus data arguments, JSON handling through json parameter and .json() method, SSL certificate verification, and connection pooling for optimal performance when making multiple API calls.
Question 85:
What is the purpose of JSON Web Tokens (JWT) in API authentication?
A) To securely transmit information between parties as digitally signed tokens containing claims
B) To encrypt entire API request and response payloads
C) To store user passwords in a hashed format
D) To establish SSL/TLS connections between clients and servers
Answer: A
Explanation:
This question examines JWT, which is widely used for stateless authentication and authorization in modern web applications and APIs. Developers must understand JWT structure and security implications when implementing authentication systems.
Option A is correct because JWT provides a compact, URL-safe method for securely transmitting information between parties as JSON objects that are digitally signed and optionally encrypted. JWTs contain claims (statements about entities and metadata) encoded in three parts: header (algorithm and token type), payload (claims), and signature (verification hash). The signature ensures token integrity, preventing tampering while allowing verification without server-side session storage. JWTs enable stateless authentication where servers don’t maintain session data, improving scalability since any server can validate tokens using shared secrets or public keys. Common claims include subject (user identifier), expiration time, issuer, and custom application-specific data. JWTs are typically included in Authorization headers using Bearer schema for API requests.
Option B describes encryption of entire payloads, which isn’t JWT’s primary purpose. While JWTs can be encrypted (JWE), standard JWTs are signed but not encrypted, with payload data base64-encoded but readable. Separate encryption mechanisms like TLS protect data in transit.
Option C refers to password hashing, which uses different algorithms like bcrypt or Argon2. JWTs don’t store passwords but rather contain claims about authenticated users after successful authentication has already occurred through other mechanisms.
Option D describes TLS/SSL establishment, which operates at the transport layer providing encryption for network communications. JWTs operate at the application layer for authentication and authorization, independent of transport security.
Developers implementing JWT should understand token expiration and refresh strategies, proper signature verification, payload validation including expiration checking, secure storage in clients, HTTPS requirements for token transmission, avoiding sensitive data in payloads since they’re decodable, and implementing proper token revocation mechanisms for security-critical applications.
Question 86:
Which design pattern is commonly used to handle asynchronous operations in JavaScript when working with APIs?
A) Promises and async/await
B) Singleton pattern
C) Factory pattern
D) Observer pattern
Answer: A
Explanation:
This question addresses asynchronous programming patterns in JavaScript, which are essential for developers working with APIs, I/O operations, and event-driven programming. Modern JavaScript development relies heavily on asynchronous patterns for responsive applications.
Option A is correct because Promises and async/await are the primary patterns for handling asynchronous operations in modern JavaScript, particularly for API calls. Promises represent eventual completion or failure of asynchronous operations, providing .then() for success handling and .catch() for error handling while avoiding callback hell through chainable operations. The async/await syntax built on Promises provides cleaner, more readable code that resembles synchronous programming while maintaining asynchronous benefits. Functions marked async automatically return Promises, and await pauses execution until Promises resolve, making sequential asynchronous operations easier to write and understand. These patterns are essential for fetch API calls, database operations, file reading, and any operations with delayed results.
Option B describes the Singleton pattern, which ensures classes have single instances with global access points. While useful for configuration managers or connection pools, Singleton doesn’t specifically address asynchronous operation handling.
Option C refers to the Factory pattern, which provides interfaces for creating objects without specifying exact classes. Factory patterns organize object creation but don’t handle asynchronous operations or timing concerns.
Option D mentions the Observer pattern, which defines one-to-many dependencies where state changes notify dependents. While relevant for event-driven programming, Observer doesn’t specifically address asynchronous operation handling like Promises do, though it may be used alongside async patterns.
Developers should master Promise chaining, error propagation through catch blocks, Promise.all() for parallel operations, Promise.race() for timeout handling, proper async function usage, error handling with try/catch in async functions, avoiding common mistakes like forgetting to return Promises in chains, and understanding microtask queues for proper execution order when combining multiple asynchronous operations.
Question 87:
What is the purpose of a webhook in API integration?
A) To enable servers to send real-time notifications to clients when specific events occur
B) To authenticate users accessing protected API endpoints
C) To compress data before transmission over networks
D) To cache frequently accessed API responses for better performance
Answer: A
Explanation:
This question examines webhooks, which are essential for event-driven architectures and real-time integrations. Developers must understand webhooks when building systems that react to external events without continuous polling.
Option A is correct because webhooks enable servers to push real-time notifications to client applications when specific events occur, implementing reverse API pattern where servers initiate communication rather than responding to client requests. When configured events happen (like payment completion, repository updates, or order status changes), the source system makes HTTP POST requests to URLs registered by client applications, delivering event data immediately. Webhooks eliminate polling inefficiency where clients repeatedly request updates, instead providing instant notifications that reduce latency, decrease network traffic, lower server load, and enable responsive applications. Webhook implementations typically include retry logic for failed deliveries, signature verification for security, and idempotency handling to manage duplicate deliveries.
Option B describes authentication mechanisms like OAuth, API keys, or JWT, which verify identity and control access. While webhooks require security measures including signature verification, their purpose is event notification rather than authentication.
Option C refers to data compression techniques like gzip or deflate applied at transport layer. Webhooks don’t inherently involve compression, though compressed data may be transmitted through webhook calls like any HTTP request.
Option D describes caching strategies that store responses for reuse, reducing backend load and improving performance. Webhooks provide real-time event delivery rather than caching previously fetched data.
Developers implementing webhooks should design endpoints that respond quickly with success codes before processing, implement signature verification to confirm legitimate sources, handle idempotency since events may be delivered multiple times, use queuing systems for reliable processing, implement exponential backoff for retries, maintain webhook endpoint availability to avoid missing events, log all webhook deliveries for debugging, and provide webhook management interfaces allowing users to register and test webhook URLs.
Question 88:
Which HTTP method should be used to update a partial resource in a RESTful API?
A) PATCH
B) POST
C) PUT
D) GET
Answer: A
Explanation:
This question addresses RESTful API design principles, specifically the semantic differences between HTTP methods when modifying resources. Understanding proper HTTP method usage ensures APIs follow REST conventions and behave predictably.
Option A is correct because PATCH is specifically designed for partial resource updates, allowing clients to send only changed fields rather than complete resource representations. PATCH requests include only fields being modified, reducing payload size and avoiding unintended changes to unspecified fields. This approach prevents race conditions where concurrent updates to different fields conflict when using PUT with complete representations. PATCH operations should be idempotent when possible, though the HTTP specification allows non-idempotent PATCH implementations. Proper PATCH implementations validate partial updates, apply changes to existing resources, and return appropriate responses indicating success or field-level validation errors.
Option B describes POST, which creates new resources or performs operations not clearly matching other methods. While POST can technically update resources, it doesn’t follow REST conventions for updates and provides less semantic clarity about the operation being performed.
Option C refers to PUT, which replaces entire resources with provided representations. PUT requires clients to send complete resource data, including unchanged fields, making it appropriate for full updates but inefficient and potentially error-prone for partial updates where clients may lack complete resource state.
Option D mentions GET, which retrieves resources without side effects. GET is explicitly defined as safe and idempotent, never modifying server state, making it inappropriate for any update operations.
Developers designing RESTful APIs should implement PATCH for partial updates alongside PUT for full replacements, validate partial update requests properly, handle missing fields appropriately by leaving them unchanged, consider using JSON Patch or JSON Merge Patch formats for standardized partial updates, return appropriate error messages for invalid field modifications, and document which fields support partial updates to guide API consumers.
Question 89:
What is the primary purpose of API rate limiting?
A) To prevent abuse and ensure fair resource usage by limiting request frequency
B) To encrypt API requests and responses for security
C) To compress data to reduce bandwidth consumption
D) To authenticate users before granting API access
Answer: A
Explanation:
This question examines rate limiting, which is a critical API management technique that developers must understand both when consuming third-party APIs and implementing their own APIs. Rate limiting protects API infrastructure while ensuring fair access.
Option A is correct because rate limiting controls request frequency to prevent abuse, ensure fair resource distribution among users, protect backend systems from overload, and maintain service quality. Rate limits typically restrict requests per time window (minute, hour, day) based on API keys, user accounts, or IP addresses. Common strategies include fixed windows (reset at intervals), sliding windows (rolling time periods), token bucket (accumulating request allowances), and leaky bucket (processing requests at steady rates). When limits are exceeded, APIs return 429 Too Many Requests status codes with Retry-After headers indicating when clients can retry. Rate limiting prevents denial-of-service attacks, constrains costs for metered backend services, enforces tiered access based on subscription levels, and protects shared infrastructure from individual user impacts.
Option B describes encryption, typically provided by TLS/SSL at transport layer. Rate limiting doesn’t involve encryption but rather controls request frequency independently of data protection mechanisms.
Option C refers to compression techniques that reduce payload sizes. While some APIs implement compression, this is separate from rate limiting, which controls request timing rather than data size.
Option D mentions authentication mechanisms that verify user identity. While rate limiting often applies per authenticated user, its purpose is controlling request frequency rather than identity verification, which happens before rate limit evaluation.
Developers consuming APIs should implement exponential backoff when encountering rate limits, monitor rate limit headers, distribute requests evenly rather than bursting, cache responses when possible, batch operations when APIs support it, and handle 429 responses gracefully. When implementing rate limiting, developers should communicate limits clearly in documentation, return informative headers showing remaining quota, implement appropriate time windows for different endpoint sensitivity levels, and consider graduated response strategies before complete blocking.
Question 90:
Which data format is commonly used for configuration files and is more human-readable than JSON?
A) YAML
B) XML
C) CSV
D) Binary
Answer: A
Explanation:
This question addresses data formats used in modern development, particularly for configuration management, CI/CD pipelines, and infrastructure as code. Understanding format characteristics helps developers choose appropriate options for different use cases.
Option A is correct because YAML (YAML Ain’t Markup Language) provides human-readable data serialization frequently used for configuration files in applications, container orchestration, CI/CD pipelines, and infrastructure definitions. YAML’s minimal syntax without brackets or quotes for simple values makes it less verbose and easier to read than JSON, supporting comments for documentation, references for avoiding duplication, and multi-line strings for better readability. YAML is used extensively in Docker Compose files, Kubernetes manifests, Ansible playbooks, GitHub Actions workflows, and application configuration. However, YAML’s significant whitespace and indentation sensitivity can cause parsing errors, and its flexibility sometimes leads to unexpected behaviors with data types.
Option B describes XML, which predates both JSON and YAML and uses verbose tag-based syntax with opening and closing elements. While XML supports complex hierarchies and namespaces, its verbosity makes it less human-readable than YAML, though more structured and validated through schemas.
Option C refers to CSV, which represents tabular data as comma-separated values. While simple and readable for spreadsheet-like data, CSV doesn’t support hierarchical structures or complex configurations, limiting its usefulness for configuration files.
Option D mentions binary formats, which are machine-readable but not human-readable. Binary formats provide compact representation and fast parsing but require tools for viewing and editing, making them inappropriate for configuration files requiring manual editing.
Developers using YAML should understand indentation significance, validate configurations using YAML linters, be aware of implicit type conversions, avoid overly complex nested structures, use consistent indentation throughout files, leverage anchors and aliases for repeated configurations, include comments for complex settings, and consider security implications of YAML parsers that might execute code in certain languages.
Question 91:
What is the purpose of CORS (Cross-Origin Resource Sharing) in web APIs?
A) To control which origins can access resources through browser-based requests
B) To encrypt data transmitted between client and server
C) To compress API responses for faster transmission
D) To authenticate users accessing protected endpoints
Answer: A
Explanation:
This question examines CORS, which is essential for developers building web applications that consume APIs from different domains. Understanding CORS prevents common development frustrations and security misconfigurations.
Option A is correct because CORS controls which origins (protocol, domain, port combinations) can access resources through browser-based requests, relaxing the same-origin policy that normally restricts cross-domain requests for security. Browsers send preflight OPTIONS requests for certain cross-origin requests, and servers respond with Access-Control-Allow-Origin headers specifying permitted origins. CORS headers also control allowed methods, headers, and whether credentials can be included. Proper CORS configuration enables legitimate cross-domain API access while preventing unauthorized origins from accessing resources. Misconfigured CORS (like wildcard origins with credentials) creates security vulnerabilities allowing malicious sites to access protected APIs.
Option B describes encryption provided by HTTPS/TLS at transport layer. CORS operates at application layer controlling access permissions, independent of encryption mechanisms protecting data in transit.
Option C refers to compression techniques typically implemented through Content-Encoding headers. CORS controls access permissions rather than data compression or transmission optimization.
Option D mentions authentication mechanisms verifying user identity. While CORS interacts with authentication (controlling credential inclusion in cross-origin requests), its purpose is controlling domain-based access rather than user authentication.
Developers should configure CORS precisely by specifying exact origins rather than wildcards when possible, never use wildcard origins with credentials, understand preflight request triggers, include appropriate headers in preflight responses, handle CORS on API gateways or reverse proxies consistently, test cross-origin requests during development, implement proper error handling for CORS failures, and document CORS requirements for API consumers needing to make browser-based requests from different domains.
Question 92:
Which Python framework is lightweight and commonly used for building RESTful APIs quickly?
A) Flask
B) NumPy
C) Pandas
D) Matplotlib
Answer: A
Explanation:
This question tests knowledge of Python web frameworks suitable for API development. Understanding framework characteristics helps developers select appropriate tools for building APIs with different requirements.
Option A is correct because Flask is a lightweight, flexible micro-framework designed for building web applications and RESTful APIs quickly with minimal boilerplate. Flask provides routing, request/response handling, and template rendering with simple decorators, allowing developers to start with minimal structure and add components as needed. Flask’s simplicity makes it ideal for small to medium APIs, prototypes, and microservices where framework overhead should be minimal. Extensions like Flask-RESTful, Flask-CORS, and Flask-JWT-Extended add REST-specific functionality, CORS handling, and authentication. Flask’s unopinionated nature gives developers freedom in architecture decisions, database choices, and project structure.
Option B describes NumPy, a numerical computing library for array operations and mathematical functions. NumPy doesn’t provide web framework capabilities and isn’t used for building APIs, though APIs might use NumPy for data processing.
Option C refers to Pandas, a data analysis library providing dataframes and data manipulation tools. Like NumPy, Pandas is used for data processing rather than building web APIs, though APIs might use Pandas internally for data transformation.
Option D mentions Matplotlib, a plotting library for creating visualizations and charts. Matplotlib generates graphics rather than handling HTTP requests or building APIs, though APIs might use it to generate chart images.
Developers using Flask for APIs should implement proper error handling with consistent response formats, use Flask-RESTFUL or similar extensions for REST conventions, implement request validation, configure CORS appropriately, add authentication and authorization, use blueprints for organizing larger applications, implement logging for debugging and monitoring, follow REST principles for resource naming and HTTP method usage, and consider Flask limitations for high-traffic scenarios where async frameworks like FastAPI might be more appropriate.
Question 93:
What is the purpose of an API schema definition like OpenAPI (Swagger)?
A) To document API endpoints, parameters, and responses in a standardized machine-readable format
B) To encrypt API traffic for secure communication
C) To store API authentication credentials securely
D) To monitor API performance and generate alerts
Answer: A
Explanation:
This question addresses API documentation and schema definitions, which are critical for API usability, integration, and maintenance. Understanding schema standards helps developers create well-documented, discoverable APIs.
Option A is correct because OpenAPI (formerly Swagger) provides standardized, machine-readable formats for documenting REST API endpoints, request parameters, response structures, authentication methods, and data models. OpenAPI specifications written in YAML or JSON describe complete API contracts including paths, operations, input validation rules, response codes, and example data. These specifications enable automatic generation of interactive documentation, client SDKs, server stubs, and testing tools. OpenAPI documentation improves developer experience, reduces integration time, enables contract-first development, supports API versioning, facilitates automated testing, and ensures consistency between documentation and implementation. Tools like Swagger UI render specifications as interactive documentation where users can explore and test endpoints.
Option B describes encryption provided by TLS/SSL at transport layer. OpenAPI documents API structure but doesn’t implement encryption or security mechanisms, though specifications can document security requirements.
Option C refers to credential storage, typically handled by secrets management systems, environment variables, or secure vaults. OpenAPI schemas document authentication methods but don’t store actual credentials.
Option D mentions monitoring and alerting, implemented through APM tools, logging systems, and monitoring platforms. OpenAPI provides documentation rather than runtime monitoring, though some tools use specifications to generate monitoring configurations.
Developers should maintain OpenAPI specifications alongside code, use specification-first or code-first approaches consistently, validate implementations against specifications, generate client libraries from specifications for consistency, include comprehensive examples, document error responses thoroughly, version specifications with APIs, use schema validation in tests, integrate specification generation into CI/CD pipelines, and keep specifications synchronized with implementation changes to maintain documentation accuracy.
Question 94:
Which HTTP header is used to specify the format of the request body in API calls?
A) Content-Type
B) Accept
C) Authorization
D) User-Agent
Answer: A
Explanation:
This question examines HTTP headers essential for API communication. Understanding header purposes enables developers to structure requests correctly and implement proper request handling in APIs.
Option A is correct because the Content-Type header specifies the media type of the request body sent to the server, informing the server how to parse the payload. Common Content-Type values include application/json for JSON data, application/x-www-form-urlencoded for HTML form submissions, multipart/form-data for file uploads, and text/xml for XML payloads. Servers use Content-Type to select appropriate parsers, validate request formats, and process data correctly. Incorrect or missing Content-Type headers cause parsing errors, 400 Bad Request responses, or incorrect data interpretation leading to application failures.
Option B describes the Accept header, which specifies formats the client can receive in responses, distinct from Content-Type that describes request body format. Accept headers enable content negotiation where servers return data in client-preferred formats.
Option C refers to the Authorization header, which carries authentication credentials like bearer tokens or basic auth. Authorization headers control access rather than describing payload formats.
Option D mentions User-Agent, which identifies the client application or browser making requests. User-Agent helps servers understand client capabilities and collect usage statistics but doesn’t describe payload formats.
Developers should always include appropriate Content-Type headers when sending request bodies, validate Content-Type values on the server side, support multiple content types when appropriate, handle unsupported media types with 415 Unsupported Media Type responses, parse bodies according to declared Content-Type rather than assuming formats, be aware that GET and DELETE typically don’t include request bodies so Content-Type is usually unnecessary, and test API behavior with various Content-Type values to ensure proper handling.
Question 95:
What is the primary advantage of using GraphQL over traditional REST APIs?
A) Clients can request exactly the data they need in a single query, reducing over-fetching and under-fetching
B) GraphQL automatically encrypts all data transmissions
C) GraphQL requires less server infrastructure than REST
D) GraphQL works only with NoSQL databases
Answer: A
Explanation:
This question examines GraphQL, an alternative to REST that addresses specific API design challenges. Understanding GraphQL advantages helps developers choose appropriate API architectures for different requirements.
Option A is correct because GraphQL enables clients to specify exactly what data they need through flexible queries, solving REST’s over-fetching (receiving unnecessary data) and under-fetching (requiring multiple requests) problems. GraphQL’s single endpoint accepts queries describing desired data structures, and servers return precisely requested fields, reducing bandwidth, improving performance, and enabling faster mobile applications. Clients can request nested related data in single queries that might require multiple REST endpoints, and fetch only necessary fields rather than complete resource representations. GraphQL’s type system enables powerful tooling, schema introspection, and compile-time validation. This flexibility benefits mobile and frontend developers who can iterate on UIs without backend changes.
Option B incorrectly suggests GraphQL provides automatic encryption. Like REST, GraphQL relies on HTTPS/TLS for encryption at transport layer rather than implementing encryption itself.
Option C claims GraphQL requires less infrastructure, which isn’t accurate. GraphQL servers often require more complex infrastructure for query parsing, execution, depth limiting, and caching compared to simpler REST implementations.
Option D incorrectly limits GraphQL to NoSQL databases. GraphQL is database-agnostic, working with SQL databases, NoSQL databases, microservices, legacy systems, or any data source through resolver functions that fetch data.
Developers implementing GraphQL should design schemas carefully considering future needs, implement query depth and complexity limits to prevent abuse, use DataLoader or similar tools to avoid N+1 query problems, implement proper authentication and authorization in resolvers, consider caching challenges since single endpoints complicate HTTP caching, document schemas thoroughly, use GraphQL-specific error handling, implement pagination for list fields, and evaluate whether GraphQL’s complexity is justified for specific use cases versus simpler REST approaches.
Question 96:
Which CI/CD practice involves automatically running tests when code changes are committed?
A) Continuous Integration
B) Continuous Deployment
C) Continuous Delivery
D) Continuous Monitoring
Answer: A
Explanation:
This question addresses CI/CD practices essential for modern software development. Understanding these practices helps developers implement automated workflows that improve code quality and accelerate delivery.
Option A is correct because Continuous Integration (CI) is the practice of automatically building and testing code whenever changes are committed to version control repositories. CI systems like Jenkins, GitLab CI, GitHub Actions, or CircleCI automatically detect commits, check out code, install dependencies, run unit tests, integration tests, linting, and code quality checks, then report results to developers. CI provides rapid feedback on code quality, detects integration issues early, prevents broken code from reaching main branches, encourages frequent commits, maintains always-releasable code, and reduces integration risks by merging changes continuously rather than in large batches.
Option B describes Continuous Deployment, which automatically deploys every change passing tests to production environments without manual intervention. While deployment includes testing, CD specifically focuses on automatic production releases rather than test execution itself.
Option C refers to Continuous Delivery, which maintains code in always-deployable states through automated testing and staging deployments, but requires manual approval for production releases. Like Continuous Deployment, the focus is on deployment readiness rather than test automation specifically.
Option D mentions Continuous Monitoring, which tracks application performance, errors, and metrics in production environments. Monitoring provides observability into running systems rather than automatically testing code changes.
Developers implementing CI should commit code frequently, maintain fast test suites to provide quick feedback, fix broken builds immediately to prevent blocking teammates, write comprehensive automated tests covering critical functionality, implement test parallelization for speed, use Docker or similar tools for consistent build environments, configure notifications for build failures, maintain separate development and production environments, implement security scanning in CI pipelines, and continuously improve test coverage and pipeline efficiency.
Question 97:
What is the purpose of containerization technologies like Docker in application development?
A) To package applications with dependencies into isolated, portable units that run consistently across environments
B) To encrypt application source code for security
C) To automatically scale applications based on demand
D) To monitor application performance and generate reports
Answer: A
Explanation:
This question examines containerization, which has transformed modern application deployment and development practices. Understanding containers helps developers build portable, consistent applications across different environments.
Option A is correct because Docker and similar containerization technologies package applications with all dependencies, libraries, configurations, and runtime environments into isolated containers that run consistently regardless of underlying infrastructure. Containers solve “works on my machine” problems by ensuring development, testing, and production environments are identical. Container images define complete application environments through Dockerfiles, enabling reproducible builds, easy sharing through registries, rapid deployment, efficient resource utilization through shared OS kernels, and simplified dependency management. Containers support microservices architectures, enable cloud-native development, facilitate CI/CD pipelines, improve development productivity, and simplify application deployment across different cloud providers or on-premise infrastructure.
Option B incorrectly suggests Docker encrypts source code. While containers can include encrypted artifacts, containerization’s purpose is environment consistency and portability rather than code encryption or security.
Option C describes auto-scaling typically provided by orchestration platforms like Kubernetes or cloud services. While containers enable scaling through rapid instantiation, containerization itself doesn’t implement automatic scaling logic.
Option D refers to application monitoring using APM tools, logging systems, or observability platforms. Containers don’t inherently provide monitoring, though containerized applications typically integrate with monitoring solutions.
Developers using containers should write efficient Dockerfiles using multi-stage builds, minimize image sizes, avoid running containers as root, scan images for vulnerabilities, use official base images, implement proper logging to stdout/stderr, externalize configuration through environment variables, mount volumes for persistent data, version images properly using tags, leverage Docker Compose for local multi-container development, and understand orchestration platforms like Kubernetes for production container management.
Question 98:
Which design principle suggests that functions should do one thing and do it well?
A) Single Responsibility Principle
B) Don’t Repeat Yourself (DRY)
C) Keep It Simple, Stupid (KISS)
D) You Aren’t Gonna Need It (YAGNI)
Answer: A
Explanation:
This question addresses software design principles that guide developers in writing maintainable, testable, and robust code. Understanding these principles helps create better software architectures and improves code quality across projects.
Option A is correct because the Single Responsibility Principle (SRP) states that functions, classes, or modules should have one clearly defined responsibility or reason to change. When functions do one thing well, they become easier to understand, test, debug, and reuse. SRP reduces coupling between different parts of code, making modifications safer since changes affect limited scope. Functions following SRP have clear names reflecting their purpose, accept focused parameters, and return predictable outputs. This principle applies across all levels from small utility functions to large microservices, promoting modular design where components have well-defined boundaries and responsibilities.
Option B describes the Don’t Repeat Yourself principle, which advocates eliminating code duplication by abstracting repeated logic into reusable functions or modules. While DRY improves maintainability, it focuses on avoiding redundancy rather than limiting function scope to single responsibilities.
Option C refers to Keep It Simple, Stupid, which encourages simple solutions over complex ones. KISS promotes straightforward implementations avoiding unnecessary complexity, but doesn’t specifically mandate that functions have single responsibilities.
Option D mentions You Aren’t Gonna Need It, which discourages implementing functionality until actually required. YAGNI prevents over-engineering and premature optimization but doesn’t specifically address function scope or single responsibilities.
Developers applying SRP should break large functions into smaller, focused functions with clear purposes, name functions descriptively reflecting their single responsibility, avoid side effects where functions modify external state unexpectedly, write unit tests that verify single behaviors, refactor functions that grow to handle multiple responsibilities, design classes with cohesive, related responsibilities, and recognize that proper function decomposition improves code readability, testability, and long-term maintainability across development teams.
Question 99:
What is the primary purpose of using environment variables in application configuration?
A) To externalize configuration values that vary between environments without changing code
B) To encrypt sensitive data stored in databases
C) To improve application performance through caching
D) To monitor system resource usage and availability
Answer: A
Explanation:
This question examines configuration management practices essential for deploying applications across multiple environments. Understanding environment variables helps developers build flexible, secure, and maintainable applications following twelve-factor app principles.
Option A is correct because environment variables externalize configuration values that differ between development, testing, staging, and production environments without requiring code changes or redeployment. Environment variables store settings like database connection strings, API endpoints, feature flags, log levels, and service credentials outside source code. This separation enables the same application code to run in different environments with appropriate configurations, improves security by keeping secrets out of version control, simplifies configuration management, supports containerized deployments where configurations inject at runtime, and follows cloud-native best practices. Environment variables can be set through shell configurations, container orchestration platforms, cloud provider settings, or CI/CD pipelines.
Option B describes data encryption, typically implemented through encryption libraries, database features, or key management services. While environment variables often store credentials for accessing encryption systems, they don’t encrypt data themselves.
Option C refers to caching strategies that improve performance by storing frequently accessed data in memory. Environment variables may configure cache settings but don’t implement caching functionality.
Option D mentions system monitoring, which tracks resource usage through monitoring agents and observability platforms. Environment variables might configure monitoring tools but don’t perform monitoring themselves.
Developers should store environment-specific configurations in environment variables, never commit secrets to version control, use .env files for local development with .gitignore entries, validate required environment variables at application startup, provide sensible defaults where appropriate, document all expected environment variables, use configuration management tools or secrets managers for production, implement proper error handling when variables are missing, consider using hierarchical configuration sources with environment variables as overrides, and rotate credentials stored in environment variables regularly following security best practices.
Question 100:
Which HTTP status code indicates that the requested resource was not found on the server?
A) 404 Not Found
B) 400 Bad Request
C) 401 Unauthorized
D) 500 Internal Server Error
Answer: A
Explanation:
This question tests understanding of HTTP status codes that communicate request outcomes between clients and servers. Proper status code usage ensures clear communication and enables appropriate error handling in applications.
Option A is correct because 404 Not Found specifically indicates the server cannot find the requested resource at the specified URI. This status code communicates that the endpoint or resource identifier is invalid, the resource was deleted, or the path contains typos. 404 responses should include helpful error messages guiding users toward valid resources or explaining why resources are unavailable. APIs return 404 when requesting non-existent resource identifiers, accessing endpoints that don’t exist, or attempting operations on deleted resources. Proper 404 handling improves user experience by clearly communicating that requests targeted invalid locations rather than encountering server errors or authentication issues.
Option B describes 400 Bad Request, which indicates malformed requests with invalid syntax, missing required parameters, or validation errors. While both 400 and 404 indicate client errors, 400 specifically means request formatting issues rather than non-existent resources.
Option C refers to 401 Unauthorized, which indicates missing or invalid authentication credentials. Resources might exist but clients cannot access them without proper authentication. 401 differs from 404 by addressing authentication rather than resource existence.
Option D mentions 500 Internal Server Error, which indicates server-side failures during request processing. 500 errors represent server problems rather than client mistakes or missing resources, requiring different troubleshooting approaches focused on server logs and application errors.
Developers should return 404 for non-existent resources rather than generic errors, include helpful error messages in response bodies, avoid exposing system details in 404 responses that could aid attackers, distinguish between 404 (not found) and 410 (permanently deleted) when appropriate, implement custom 404 pages for user-facing applications, log 404 errors to identify broken links or API usage issues, use 404 consistently across API endpoints, and consider returning 404 versus 403 carefully to avoid information disclosure about resource existence to unauthorized users.
