Node.js dns.resolveCname() Method

The dns.resolveCname() method is an inbuilt application programming interface of the dns module which is used to resolve CNAME records for the specified hostname using DNS protocol.

Syntax:

dns.resolveCname( hostname, callback )

Parameters: This method has two parameters as mentioned above and described below:

• hostname: This parameter specifies a string which denotes the hostname to be resolved.
• callback: It specifies a function to be called after DNS resolution of the hostnames.
  • error: It specifies error if generated.
  • addresses: It is an array of string that signifies the returned cname addresses for the hostname.

Return Value: This method returns error, addresses through callback function, These data are passed as parameters to the callback function.

Below examples illustrate the use of dns.resolveCname() method in Node.js:

Example 1:

// Node.js program to demonstrate the
// dns.resolveAny() method

// Accessing dns module
const dns = require('dns');

// Calling dns.resolveCname() method for hostname
// geeksforgeeks.org and displaying them in
// console as a callback
dns.resolveCname('geeksforgeeks.org', (err,
    addresses) => console.log('addresses: %j', addresses));

Output:

QueryReqWrap {
  bindingName: 'queryCname',
  callback: [Function],
  hostname: 'geeksforgeeks.org',
  oncomplete: [Function: onresolve],
  ttl: false,
  channel: ChannelWrap {} }
addresses: undefined

Example 2:

// Node.js program to demonstrate the
// dns.resolveAny() method

// Accessing dns module
const dns = require('dns');

// Calling dns.resolveCname() method for hostname
// geeksforgeeks.org and displaying them in
// console as a callback
dns.resolveCname('localhost', (err,
    addresses) => console.log('addresses: %j', addresses));

Output:

QueryReqWrap {
  bindingName: 'queryCname',
  callback: [Function],
  hostname: 'localhost',
  oncomplete: [Function: onresolve],
  ttl: false,
  channel: ChannelWrap {} }
addresses: undefined

Note: The above program will compile and run by using the node index.js command.

Reference: https://nodejs.org/api/dns.html#dns_dns_resolvecname_hostname_callback