Node.js dns.resolve() Method

The dns.resolve() method is an inbuilt application programming interface of the dns module which is used to resolve hostname into an array of the resource records.

Syntax:

dns.resolve( hostname, rrtype, 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.
• rrtype: It specifies the resource record type. Its default value is ‘A’. The list of records (‘A’, ‘AAAA’, ‘ANY’, ‘CNAME’, ‘MX’, ‘TXT’, ‘NS’, ‘NAPTR’, ‘PTR’, ‘SOA’, ‘SRV’) are described below:
  • A: IPv4 address
  • AAAA: IPv6 address
  • ANY: Any records
  • CNAME: canonical name records
  • MX: mail exchange records
  • NAPTR: name authority pointer records
  • NS: name server records
  • PTR: pointer records
  • SOA: start of authority records
  • SRV: service records
  • TXT: text records
• callback: It specifies a function which to be called after DNS resolution of the hostname.
  • error: It specifies error if generated.
  • records: It’s string or object that signifies the returned record.

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

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

Example 1:








// Node.js program to demonstrate the    // dns.resolve() method    // Accessing dns module const dns = require('dns');    // Set the rrtype for dns.resolve() method const rrtype="A";    // Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err, records)          => console.log('records: %j', records));

Output:

records: ["34.218.62.116"]

Example 2:








// Node.js program to demonstrate the    // dns.resolve() method    // Accessing dns module const dns = require('dns');    // Set the rrtype for dns.resolve() method const rrtype="MX";    // Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err, records)              => console.log('records: %j', records));

Output:

records: [
    {"exchange":"alt1.aspmx.l.google.com", "priority":5},
    {"exchange":"alt2.aspmx.l.google.com", "priority":5},
    {"exchange":"aspmx.l.google.com", "priority":1},
    {"exchange":"alt3.aspmx.l.google.com", "priority":10},
    {"exchange":"alt4.aspmx.l.google.com", "priority":10}
]

Example 3:








// Node.js program to demonstrate the    // dns.resolve() method    // Accessing dns module const dns = require('dns');    // Set the rrtype for dns.resolve() method const rrtype="TXT";    // Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err,      records) => console.log('records: %j', records));

Output:

records: [
    ["v=spf1 include:amazonses.com include:_spf.google.com -all"],
    ["fob1m1abcdp777bf2ncvnjm08n"]
]

Example 4:








// Node.js program to demonstrate the    // dns.resolve() method    // Accessing dns module const dns = require('dns');    // Set the rrtype for dns.resolve() method const rrtype="NS";    // Calling dns.resolve() method for hostname // geeksforgeeks.org and print them in // console as a callback dns.resolve('geeksforgeeks.org', rrtype, (err,      records) => console.log('records: %j', records));

Output:

records: [
    "ns-1520.awsdns-62.org", 
    "ns-1569.awsdns-04.co.uk",
    "ns-245.awsdns-30.com",
    "ns-869.awsdns-44.net"
]

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

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



Learn to code easily with our course Coding for Everyone. This course is accessible and designed for everyone, even if you're new to coding. Start today and join millions on a journey to improve your skills!

Whether you're preparing for your first job interview or aiming to upskill in this ever-evolving tech landscape, GeeksforGeeks Courses are your key to success. We provide top-quality content at affordable prices, all geared towards accelerating your growth in a time-bound manner. Join the millions we've already empowered, and we're here to do the same for you. Don't miss out - check it out now!

Commit to GfG's Three-90 Challenge! Purchase a course, complete 90% in 90 days, and save 90% cost click here to explore.
Last Updated : 13 Oct, 2021
Like Article
Save Article
Previous
Node.js dns.lookupService() Method
Next
Node.js dns.resolve4() Method
Share your thoughts in the comments
Add Your Comment
Please Login to comment...