Node.js dns.resolveCname() Method

Last Updated : 13 Oct, 2021
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: javascript
// 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: javascript
// 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
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