[PR #2928] [MERGED] Filter invalid DNS server addresses on windows OS #3431

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opened 2026-03-16 11:43:21 +03:00 by kerem · 0 comments

kerem commented

2026-03-16 11:43:21 +03:00

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📋 Pull Request Information

Original PR: https://github.com/hickory-dns/hickory-dns/pull/2928
Author: @watertreestar
Created: 4/13/2025
Status: ✅ Merged
Merged: 4/22/2025
Merged by: @djc

Base: main ← Head: windows-rfc3879

📝 Commits (1)

613a462 Filter invalid DNS server addresses on windows OS

📊 Changes

1 file changed (+16 additions, -1 deletions)

View changed files

📝 crates/resolver/src/system_conf/windows.rs (+16 -1)

📄 Description

Background

Windows systems set IPv6 site-local anycast DNS addresses with the fec0::/10 prefix by default when no other IPv6 DNS addresses are configured. However, these addresses have been deprecated since 2004 as per RFC 3879. Using these deprecated addresses may cause DNS resolution issues or unnecessary resolution attempts.
Due to this issue, when using the http module in Deno, requests become exceptionally slow, while using fetch does not exhibit this behavior.

Solution

This PR adds filtering logic for DNS server addresses in Windows system configuration, skipping IPv6 addresses that start with 0xfe and 0xc0 (i.e., addresses with the fec0::/10 prefix). This avoids using these deprecated DNS server addresses, improving resolution reliability.

Fixes #1968

_{🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.}

## 📋 Pull Request Information **Original PR:** https://github.com/hickory-dns/hickory-dns/pull/2928 **Author:** [@watertreestar](https://github.com/watertreestar) **Created:** 4/13/2025 **Status:** ✅ Merged **Merged:** 4/22/2025 **Merged by:** [@djc](https://github.com/djc) **Base:** `main` ← **Head:** `windows-rfc3879` --- ### 📝 Commits (1) - [`613a462`](https://github.com/hickory-dns/hickory-dns/commit/613a4627b8127a46ddcbbf9f0cf8abab062670ea) Filter invalid DNS server addresses on windows OS ### 📊 Changes **1 file changed** (+16 additions, -1 deletions) <details> <summary>View changed files</summary> 📝 `crates/resolver/src/system_conf/windows.rs` (+16 -1) </details> ### 📄 Description ### Background Windows systems set IPv6 site-local anycast DNS addresses with the fec0::/10 prefix by default when no other IPv6 DNS addresses are configured. However, these addresses have been deprecated since 2004 as per RFC 3879. Using these deprecated addresses may cause DNS resolution issues or unnecessary resolution attempts. Due to this issue, when using the http module in Deno, requests become exceptionally slow, while using fetch does not exhibit this behavior. ### Solution This PR adds filtering logic for DNS server addresses in Windows system configuration, skipping IPv6 addresses that start with 0xfe and 0xc0 (i.e., addresses with the fec0::/10 prefix). This avoids using these deprecated DNS server addresses, improving resolution reliability. Fixes #1968 --- <sub>🔄 This issue represents a GitHub Pull Request. It cannot be merged through Gitea due to API limitations.</sub>