dns.resolve()

Resolves the given hostname to a DNS record.

This is an asynchronous function that returns a Promise.

Syntax

let resolving = browser.dns.resolve(
  hostname,    // string
  flags        // array of string
)

Parameters

• hostname
  • : string. The hostname to resolve.
• flags {{optional_inline}}
  • : array of string. Flags to modify the way the hostname is resolved. Any omitted flags default to false. You can pass zero or more of the following flags:
    • "allow_name_collisions": Allow name collision results which are normally filtered out.
    • "bypass_cache": Suppresses the internal DNS lookup cache.
    • "canonical_name": The canonical name of the specified host will be queried.
    • "disable_ipv4": Only IPv6 addresses will be returned.
    • "disable_ipv6": Only IPv4 addresses will be returned.
    • "disable_trr": Do not use the Trusted Recursive Resolver (TRR) for resolving the host name. A TRR enables resolving of host names using a dedicated DNS-over-HTTPS server.
    • "offline": Only literals and cached entries will be returned.
    • "priority_low": The request is given lower priority. If "priority_medium" is also given, the query is given medium priority.
    • "priority_medium": The request is given medium priority. If "priority_low" is also given, the query is given medium priority.
    • "speculate": Indicates that the request is speculative. Speculative requests return errors if prefetching is disabled by the browser's configuration.

Return value

A Promise that will be fulfilled with a DNSRecord object. This object can contain the following properties:

• addresses
  • : array of string. The IP addresses associated with this DNS record.
• canonicalName
  • : string. The canonical name for this record. This is only included in the response if the "canonical_name" flag was passed to resolve().
• isTRR
  • : boolean: true if the record was retrieved using a Trusted Recursive Resolver (TRR).

Examples

function resolved(record) {
  console.log(record.addresses);
}

let resolving = browser.dns.resolve("example.com");
resolving.then(resolved);

// > e.g. Array [ "192.0.2.172" ]

Bypass the cache, and ask for the canonical name:

function resolved(record) {
  console.log(record.canonicalName);
  console.log(record.addresses);
}

let resolving = browser.dns.resolve("developer.mozilla.org", [
  "bypass_cache",
  "canonical_name",
]);
resolving.then(resolved);

// > e.g. xyz.us-west-2.elb.amazonaws.com
// > e.g. Array [ "192.0.2.172", "198.51.100.45" ]

{{WebExtExamples}}

Browser compatibility

{{Compat}}