Node.js DNS

by Online Tutorials Library July 14, 2022

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.tutoraspire.com’, (err, addresses, family) => {   console.log(‘addresses:’, addresses);   console.log(‘family:’,family); }); 

Open Node.js command prompt and run the following code:

Node.js dns example 1

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.tutoraspire.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.js dns example 2

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.js dns example 3

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Node.js DNS

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Node.js DNS Example 1

Node.js DNS Example 2

Node.js DNS Example 3

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