DevOps Error ENOTFOUND Beginner 15 views

Node.js ENOTFOUND

DNS lookup failed because the hostname could not be resolved.

Explanation

ENOTFOUND occurs when the DNS (Domain Name System) lookup for a hostname fails, meaning the hostname could not be resolved to an IP address. This is a common Node.js error when making HTTP requests, connecting to databases, or reaching any network service. Common causes include the hostname being misspelled, DNS server being unreachable, the domain not existing, local hosts file missing an entry, or temporary DNS resolution failures. The error includes the hostname that failed to resolve.

Common Causes

Hostname misspelled
DNS server unreachable
Domain doesn't exist or expired
Local hosts file missing entry
Temporary DNS failure

Solution

Verify the hostname is spelled correctly. Check DNS resolution: nslookup hostname or dig hostname. Test if DNS servers are reachable. Check /etc/hosts for local entries. Try using the IP address directly to bypass DNS. Flush DNS cache: sudo dscacheutil -flushcache (Mac) or sudo systemctl restart nscd (Linux). Check network connectivity. Verify the domain exists and hasn't expired. For local development, ensure /etc/hosts or equivalent has the correct entries. Use environment variables for hostnames to avoid hardcoding.

Code Example

// ENOTFOUND when connecting to service
const mysql = require('mysql2');
const connection = mysql.createConnection({
    host: 'mydb.local',  // DNS resolution fails!
    user: 'root'
});

connection.connect((err) => {
    if (err && err.code === 'ENOTFOUND') {
        console.error('Cannot resolve hostname:', err.hostname);
    }
});

// Fix: check DNS resolution
const dns = require('dns');
dns.lookup('mydb.local', (err, address) => {
    if (err) {
        console.error('DNS failed:', err.message);
    } else {
        console.log('Resolved to:', address);
    }
});

// Use IP directly for testing
const connection = mysql.createConnection({
    host: '127.0.0.1',  // bypass DNS
    user: 'root'
});

// Check DNS from command line
nslookup mydb.local
dig mydb.local

// Flush DNS cache (Mac)
sudo dscacheutil -flushcache
sudo killall -HUP mDNSResponder

Error Information

Language

javascript

Framework

nodejs

Difficulty

Beginner

Views

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Code Example

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