Node.js DNS
The Node.js DNS module contains methods to get information of given hostname. Let's see the list of commonly used DNS functions:
- dns.getServers()
- dns.setServers(servers)
- dns.lookup(hostname[, options], callback)
- dns.lookupService(address, port, callback)
- dns.resolve(hostname[, rrtype], callback)
- dns.resolve4(hostname, callback)
- dns.resolve6(hostname, callback)
- dns.resolveCname(hostname, callback)
- dns.resolveMx(hostname, callback)
- dns.resolveNs(hostname, callback)
- dns.resolveSoa(hostname, callback)
- dns.resolveSrv(hostname, callback)
- dns.resolvePtr(hostname, callback)
- dns.resolveTxt(hostname, callback)
- dns.reverse(ip, callback)
Node.js DNS Example 1
Let's see the example of dns.lookup() function.
File: dns_example1.js
- const dns = require('dns');
- dns.lookup('www.javatpoint.com', (err, addresses, family) => {
- console.log('addresses:', addresses);
- console.log('family:',family);
- });
Open Node.js command prompt and run the following code:
- node dns_example1.js
Node.js DNS Example 2
Let's see the example of resolve4() and reverse() functions.
File: dns_example2.js
- const dns = require('dns');
- dns.resolve4('www.javatpoint.com', (err, addresses) => {
- if (err) throw err;
- console.log(`addresses: ${JSON.stringify(addresses)}`);
- addresses.forEach((a) => {
- dns.reverse(a, (err, hostnames) => {
- if (err) {
- throw err;
- }
- console.log(`reverse for ${a}: ${JSON.stringify(hostnames)}`);
- });
- });
- });
Open Node.js command prompt and run the following code:
- node dns_example2.js
Node.js DNS Example 3
Let's take an example to print the localhost name using lookupService() function.
File: dns_example3.js
- const dns = require('dns');
- dns.lookupService('127.0.0.1', 22, (err, hostname, service) => {
- console.log(hostname, service);
- // Prints: localhost
- });
Open Node.js command prompt and run the following code:
- node dns_example3.js
