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Node Js · Question Set
Networking & Security interview questions for placements and exams.
Questions
14
Included in this set
Subject
Node Js
Explore more sets
Difficulty
Mixed
Level of this set
Go through each question and its explanation. Use this set as a focused practice pack for Node Js.
Middleware functions in Node.js (especially in Express) process incoming requests before they reach route handlers. They can modify requests, add headers, handle authentication, or terminate the request-response cycle.
app.use((req,res,next)=>{
console.log('Request Time:', Date.now());
next();
});For complete preparation, combine this set with full subject-wise practice for Node Js. You can also explore other subjects and sets from the links below.
Use `fs.stat()` to get metadata like size, creation date, and modification time. It’s asynchronous and part of the core `fs` module.
const fs=require('fs');
fs.stat('file.txt',(err,stats)=>console.log(stats.size));TLS (Transport Layer Security) encrypts data between client and server, preventing eavesdropping and tampering. Node’s `https` and `tls` modules enable secure communication using certificates.
The crypto module enables secure data encryption, hashing, and signing. It supports algorithms like AES, RSA, and SHA, helping developers secure passwords, tokens, and sensitive data.
const crypto=require('crypto');
const hash=crypto.createHash('sha256').update('secret').digest('hex');
console.log(hash);MongoDB connects through the official driver or Mongoose. The `connect()` function establishes a persistent connection, and once connected, it can perform CRUD operations efficiently.
const mongoose=require('mongoose');
mongoose.connect('mongodb://localhost:27017/mydb');NODE_ENV defines the environment in which the app runs — 'development', 'test', or 'production'. It controls configuration like logging, performance optimization, and debug settings. Production mode improves speed and disables verbose logs.
The `dns.lookup()` method converts domain names into IP addresses. It’s part of Node’s built-in `dns` module and is used internally by HTTP requests to resolve hostnames before making connections.
const dns=require('dns');
dns.lookup('google.com',(err,address)=>console.log(address));Node’s `https` module lets you create secure servers using SSL/TLS certificates. HTTPS ensures encrypted communication between clients and servers, preventing eavesdropping and data tampering.
const https=require('https');
const fs=require('fs');
const opts={key:fs.readFileSync('key.pem'),cert:fs.readFileSync('cert.pem')};
https.createServer(opts,(req,res)=>res.end('Secure!')).listen(443);Node.js implements sandboxing to isolate code, uses TLS/SSL for encryption, environment variables for secrets, and libraries like Helmet for securing HTTP headers. Regular dependency audits also prevent known vulnerabilities.
Passport.js is a flexible authentication middleware for Node.js. It supports local logins and social logins (Google, Facebook, GitHub). It simplifies user authentication by using modular strategies.
const passport=require('passport');
app.post('/login',passport.authenticate('local'),(req,res)=>res.send('Logged in'));Punycode converts Unicode domain names (like emoji or non-English characters) into ASCII format for DNS compatibility. Node.js includes the Punycode module for backward compatibility with international domains.
const punycode=require('punycode/');
console.log(punycode.encode('mañana'));Yes. You can run `node inspect app.js` to debug applications. The built-in debugger allows step-by-step execution, variable inspection, and breakpoints using Chrome DevTools or VSCode integration.
node inspect index.js // open chrome://inspect for debugging
Node.js supports all standard HTTP request methods such as GET (fetch data), POST (create data), PUT (update data), DELETE (remove data), PATCH (partial update), and HEAD (metadata only). These can be implemented using the `http` or `express` modules.
app.get('/users',(req,res)=>res.send('List'));
app.post('/users',(req,res)=>res.send('Created'));`fs.readFile()` reads the entire file into memory before processing, making it suitable for small files. `fs.createReadStream()` reads chunks of data as streams, ideal for large files or real-time data transfer.
fs.createReadStream('large.txt').pipe(fs.createWriteStream('copy.txt'));