Well the Node.js DNS module will mainly contains methods to get information of given hostname. And below is 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 have a example of dns.lookup() function.
File: dnsexample1.js
const dns = require('dns');
dns.lookup('www.javatpoint.com', (err, addresses, family) => {
console.log('addresses:', addresses);
console.log('family:',family);
});
Now we will open Node.js command prompt and the run the below code:-
node dnsexample1.js
Node.js DNS Example 2
Now lets have one example with resolve4() and reverse() functions.
File: dnsexample2.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)}`);
});
});
});
Now open the Node.js command prompt and run the below code
node dnsexample2.js
Node.js DNS Example 3
Now let's take an example to print the localhost name by using lookupService() function.
File: dnsexample3.js
const dns = require('dns');
dns.lookupService('127.0.0.1', 22, (err, hostname, service) => {
console.log(hostname, service);
// Prints: localhost
});
Now open the Node.js command prompt and run the below code:
node dnsexample3.js
