Class Resolver

An independent resolver for DNS requests.

Creating a new resolver uses the default server settings. Setting the servers used for a resolver using resolver.setServers() does not affect other resolvers:

import { Resolver } from 'node:dns';
const resolver = new Resolver();
resolver.setServers(['4.4.4.4']);

// This request will use the server at 4.4.4.4, independent of global settings.
resolver.resolve4('example.org', (err, addresses) => {
  // ...
});

The following methods from the node:dns module are available:

  • resolver.getServers()
  • resolver.resolve()
  • resolver.resolve4()
  • resolver.resolve6()
  • resolver.resolveAny()
  • resolver.resolveCaa()
  • resolver.resolveCname()
  • resolver.resolveMx()
  • resolver.resolveNaptr()
  • resolver.resolveNs()
  • resolver.resolvePtr()
  • resolver.resolveSoa()
  • resolver.resolveSrv()
  • resolver.resolveTxt()
  • resolver.reverse()
  • resolver.setServers()

Since

v8.3.0

Constructors

constructor

Properties

getServers resolve resolve4 resolve6 resolveAny resolveCaa resolveCname resolveMx resolveNaptr resolveNs resolvePtr resolveSoa resolveSrv resolveTlsa resolveTxt reverse setServers

Methods

cancel setLocalAddress

Constructors

constructor

Properties

getServers

getServers: (() => string[])

Type declaration

    • (): string[]

    • Returns an array of IP address strings, formatted according to RFC 5952, that are currently configured for DNS resolution. A string will include a port section if a custom port is used.

      [
        '4.4.4.4',
        '2001:4860:4860::8888',
        '4.4.4.4:1053',
        '[2001:4860:4860::8888]:1053',
      ]

      Returns string[]

      Since

      v0.11.3

resolve

resolve: typeof resolve

resolve4

resolve4: typeof resolve4

resolve6

resolve6: typeof resolve6

resolveAny

resolveAny: typeof resolveAny

resolveCaa

resolveCaa: typeof resolveCaa

resolveCname

resolveCname: typeof resolveCname

resolveMx

resolveMx: typeof resolveMx

resolveNaptr

resolveNaptr: typeof resolveNaptr

resolveNs

resolveNs: typeof resolveNs

resolvePtr

resolvePtr: typeof resolvePtr

resolveSoa

resolveSoa: typeof resolveSoa

resolveSrv

resolveSrv: typeof resolveSrv

resolveTlsa

resolveTlsa: typeof resolveTlsa

resolveTxt

resolveTxt: typeof resolveTxt

reverse

reverse: ((ip: string, callback: ((err: null | ErrnoException, hostnames: string[]) => void)) => void)

Type declaration

    • (ip, callback): void

    • Performs a reverse DNS query that resolves an IPv4 or IPv6 address to an array of host names.

      On error, err is an Error object, where err.code is one of the DNS error codes.

      Parameters

      • ip: string
      • callback: ((err: null | ErrnoException, hostnames: string[]) => void)
          • (err, hostnames): void

          • Parameters

            Returns void

      Returns void

      Since

      v0.1.16

setServers

setServers: ((servers: readonly string[]) => void)

Type declaration

    • (servers): void

    • Sets the IP address and port of servers to be used when performing DNS resolution. The servers argument is an array of RFC 5952 formatted addresses. If the port is the IANA default DNS port (53) it can be omitted.

      dns.setServers([
        '4.4.4.4',
        '[2001:4860:4860::8888]',
        '4.4.4.4:1053',
        '[2001:4860:4860::8888]:1053',
      ]);

      An error will be thrown if an invalid address is provided.

      The dns.setServers() method must not be called while a DNS query is in progress.

      The setServers method affects only resolve, dns.resolve*() and reverse (and specifically not lookup).

      This method works much like resolve.conf. That is, if attempting to resolve with the first server provided results in a NOTFOUND error, the resolve() method will not attempt to resolve with subsequent servers provided. Fallback DNS servers will only be used if the earlier ones time out or result in some other error.

      Parameters

      • servers: readonly string[]

        array of RFC 5952 formatted addresses

      Returns void

      Since

      v0.11.3

Methods

cancel

  • cancel(): void

  • Cancel all outstanding DNS queries made by this resolver. The corresponding callbacks will be called with an error with code ECANCELLED.

    Returns void

    Since

    v8.3.0

setLocalAddress

  • setLocalAddress(ipv4?, ipv6?): void

  • The resolver instance will send its requests from the specified IP address. This allows programs to specify outbound interfaces when used on multi-homed systems.

    If a v4 or v6 address is not specified, it is set to the default and the operating system will choose a local address automatically.

    The resolver will use the v4 local address when making requests to IPv4 DNS servers, and the v6 local address when making requests to IPv6 DNS servers. The rrtype of resolution requests has no impact on the local address used.

    Parameters

    • Optionalipv4: string

      A string representation of an IPv4 address.

    • Optionalipv6: string

      A string representation of an IPv6 address.

    Returns void

    Since

    v15.1.0, v14.17.0

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