nodejs / nodejs/node

dns.resolveSrv returns ECONNREFUSED on Windows since v24.13.0 (still broken in v25.x and v26.x)

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Description

Version

v24.14.0, v25.8.1

Platform
Microsoft Windows NT 10.0.26200.0 x64
Subsystem

dns (c-ares)

What steps will reproduce the bug?

Run the following script:

const dns = require("dns");

dns.resolveSrv("_mongodb._tcp.mongodb.<your-cluster>.mongodb.net", (err, addresses) => {
  console.log(err ? `error ${err.code}: ${err.message}` : addresses);
});

Run with Node.js >= v24.13.0 on Windows.

How often does it reproduce? Is there a required condition?

100% reproducible on Windows.

No special conditions required.

What is the expected behavior? Why is that the expected behavior?

The SRV query should resolve successfully and return records.

Example output (Node v24.12.0 and v25.2.1):

[
  {
    name: 'shard-00-00.<your-cluster>.mongodb.net',
    port: 27017,
    priority: 0,
    weight: 0,
    type: 'SRV'
  },
  {
    name: 'shard-00-01.<your-cluster>.mongodb.net',
    port: 27017,
    priority: 0,
    weight: 0,
    type: 'SRV'
  },
  {
    name: 'shard-00-02.<your-cluster>.mongodb.net',
    port: 27017,
    priority: 0,
    weight: 0,
    type: 'SRV'
  }
]

This behavior is consistent with:

  • previous Node.js versions
  • Node.js v25.2.1
  • other platforms (tested on Linux)
What do you see instead?
error ECONNREFUSED: querySrv ECONNREFUSED _mongodb._tcp.<your-cluster>.mongodb.net

This happens consistently even with valid public DNS resolvers configured on the system.

Additional information

This appears related to the issue described in #61435 and the fix in #61453 (commit 17b363a66c).

However, the problem persists on Windows.

From testing:

  • Node.js 24:

    • Last known working version: v24.12.0
    • First broken version: v24.13.0+
  • Node.js 25:

    • Last known working version: v25.2.1
    • Reproducible in all tested versions up to v25.8.1

The issue is 100% reproducible and specifically affects SRV resolution (dns.resolveSrv).

The issue does not occur in earlier versions and is therefore a regression.

This suggests the fix may be incomplete or that the regression was reintroduced.

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the dns.resolveSrv reproduction in the issue and compare the changes from commit 17b363a66c and issue #61435, including the fix tracked in #61453. Reproduce the ECONNREFUSED result on Windows against the listed Node.js versions and verify that SRV queries again return records without regressing other platforms.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, node.js
Domain
networking
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Quiet
Clarity
Mostly clear
Newbie friendliness
45/100

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