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:
// 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));
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Output:
PTR records:[{"34.218.62.116"}]
Example 2:
// 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));
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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