Node.js dns.resolve() Method

Last Updated : 10 Sep, 2024

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:

javascript

// 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: ["8.8.8.8"]
```
Example 2:

javascript

// 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:

javascript

// 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:

javascript

// 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

Node.js dns.resolve4() Method

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