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Node.js dns.resolve4() Method

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The dns.resolve4() method is an inbuilt application programming interface of the dns module which is used to resolve IPv4 address (‘A’ record) for the specified hostname using DNS protocol.

Syntax:

dns.resolve4( hostname, options, callback )

Parameters: This method accept three parameters as mentioned above and described below:

  • hostname: This parameter specifies a string which denotes the hostname to be resolved.
  • options: It is in the form of an object.
    • ttl: It is a Boolean parameter specifies whether the Time-To-Live value (TTL) for each record to be retrieved or not. If set to true, TTL for each record is retrieved (in seconds).
  • callback: It specifies a function to be called after DNS resolution of the hostname.
    • error: It specifies error if generated.
    • address: It is a string or object that signifies the returned IPv4 address(es) for the hostname.

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

Below examples illustrate the use of dns.resolve4() Method in Node.js:

Example 1:




// Node.js program to demonstrate the   
// dns.resolve4() method
  
// Accessing dns module
const dns = require('dns');
  
// Calling dns.resolve4() method for hostname
// geeksforgeeks.org and display them in
// console as a callback
dns.resolve4('geeksforgeeks.org', (err,
    address) => console.log('address: %j', address));


Output:

address: ["34.218.62.116"]

Example 2:




// Node.js program to demonstrate the   
// dns.resolve4() method
  
// Accessing dns module
const dns = require('dns');
  
// Setting options value for
// dns.resolve4() method
const options = {
    ttl: true,
};
  
// Calling dns.resolve4() method for hostname
// geeksforgeeks.org and displaying them
// in console as a callback
dns.resolve4('geeksforgeeks.org', options, (err,
    address) => console.log('address: %j', address));


Output:

address: [{"address":"34.218.62.116", "ttl":9}]

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

Reference: https://nodejs.org/api/dns.html#dns_dns_resolve4_hostname_options_callback



Last Updated : 13 Oct, 2021
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