How to fix Error: DNS timeout in Node.js

# Test DNS resolution manually
nslookup example.com
dig example.com

# Check your DNS configuration
cat /etc/resolv.conf

const dns = require('dns').promises;
const cache = new Map();

async function cachedLookup(hostname) {
  const now = Date.now();
  const cached = cache.get(hostname);

  // Use cached result if still valid (60 second TTL)
  if (cached && now - cached.timestamp < 60000) {
    return cached.address;
  }

  const { address } = await dns.lookup(hostname);
  cache.set(hostname, { address, timestamp: now });
  return address;
}

// Usage
try {
  const ip = await cachedLookup('example.com');
  console.log('Resolved IP:', ip);
} catch (err) {
  console.error('DNS lookup failed:', err);
}

const dns = require('dns');
const { Resolver } = dns;

const resolver = new Resolver();

// Set custom DNS servers
resolver.setServers(['8.8.8.8', '1.1.1.1']);

// Resolve with timeout handling
const timeoutPromise = new Promise((_, reject) =>
  setTimeout(() => reject(new Error('DNS timeout')), 5000)
);

const resolvePromise = new Promise((resolve, reject) => {
  resolver.resolve4('example.com', (err, addresses) => {
    if (err) reject(err);
    else resolve(addresses);
  });
});

try {
  const addresses = await Promise.race([resolvePromise, timeoutPromise]);
  console.log('Resolved addresses:', addresses);
} catch (err) {
  console.error('DNS resolution failed:', err.message);
}

# Set before starting Node.js
export UV_THREADPOOL_SIZE=128
node app.js

process.env.UV_THREADPOOL_SIZE = 128;

// Now start your application
const http = require('http');
// ... rest of your code

const dns = require('dns').promises;

// Instead of dns.lookup() which blocks the threadpool
async function resolveHostname(hostname) {
  try {
    // Use resolve4/resolve6 which don't block threadpool
    const addresses = await dns.resolve4(hostname);
    return addresses[0]; // Return first IP
  } catch (err) {
    console.error('DNS resolution failed:', err.message);
    throw err;
  }
}

// Usage
resolveHostname('example.com')
  .then(ip => console.log('Resolved IP:', ip))
  .catch(err => console.error('Error:', err));

# Set retry and timeout parameters
export RES_OPTIONS='retrans:1000 retry:3 rotate'
node app.js

# Install dnsmasq (Ubuntu/Debian)
sudo apt-get install dnsmasq

# Configure it to cache DNS queries
sudo systemctl start dnsmasq
sudo systemctl enable dnsmasq

# Point Node.js to use localhost DNS
# Edit /etc/resolv.conf
nameserver 127.0.0.1