Node.js dns.resolvePtr() Method (original) (raw)

Last Updated : 13 Oct, 2021

The dns.resolvePtr() method is an inbuilt application programming interface of the dns module which is used to resolve PTR or pointer records for the specified hostname using DNS protocol.Syntax:

dns.resolvePtr( 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 pointer records 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.resolvePtr(); Method in Node.js:Example 1:

javascript `

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

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

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

`

Output:

PTR records:[{"34.218.62.116"}]

Example 2:

javascript `

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

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

// Calling dns.resolvePtr() method for hostname // google.com and displaying them in // console as a callback dns.resolvePtr('google.com', (err, addresses) => console.log('PTR records: %j', addresses));

`

Output:

PTR records:[{"172.217.164.142"}]

Note: The above program will compile and run by using the node index.js command.Reference: https://nodejs.org/api/dns.html#dns_dns_resolveptr_hostname_callback