[ci-scan] Known Build Error: System.Net.NameResolution DnsGetHostAddresses_LocalhostSubdomainWithTrailingDot fails on Android

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On Android (runtime-extra-platforms, android-arm64 CoreCLR leg), the test System.Net.NameResolution.Tests.GetHostAddressesTest.DnsGetHostAddresses_LocalhostSubdomainWithTrailingDot_ReturnsLoopback fails because the Android DNS resolver returns link-local and globally-routable IPv6 addresses for .localhost subdomain queries instead of loopback addresses.

The test expects that hostnames like foo.localhost. and bar.test.localhost. resolve to loopback (127.0.0.1 or ::1), per RFC 6761 §6.3. The Android emulator's DNS resolver does not honour this RFC for subdomains of localhost, returning addresses such as fe80::2dd7:ff44:eff:c764%30 and 2001:4898:502:2:8b82:8144:4cea:2b6d instead.

Impact on platforms

• runtime-extra-platforms (def 154) · android-arm64 CoreCLR · Ubuntu.2204.Amd64.Android.29.Open · no stress · exit code 1

Errors log

[FAIL] System.Net.NameResolution.Tests.GetHostAddressesTest.DnsGetHostAddresses_LocalhostSubdomainWithTrailingDot_ReturnsLoopback(hostName: "foo.localhost.")
Assert.All() Failure: 7 out of 8 items in the collection did not pass.
[1]: Item:  fe80::2dd7:ff44:eff:c764%30
     Error: Expected loopback address but got: fe80::2dd7:ff44:eff:c764%30
[2]: Item:  2001:4898:502:2:8b82:8144:4cea:2b6d
     Error: Expected loopback address but got: 2001:4898:502:2:8b82:8144:4cea:2b6d

First build it occurred

runtime-extra-platforms build 1411505 — finished 2026-05-07. Also present in latest build 1413202. ≥2 occurrences in the scanned window. Note: this is computed within the ~10-build scan window and may not be the true origin.

Recommended action

Skip DnsGetHostAddresses_LocalhostSubdomainWithTrailingDot_ReturnsLoopback on TestPlatforms.Android via [ActiveIssue]. This is a platform DNS resolver behaviour difference, not a .NET product bug. The muting PR will follow in the next ci-scan run.

{
  "ErrorMessage": "DnsGetHostAddresses_LocalhostSubdomainWithTrailingDot_ReturnsLoopback",
  "BuildRetry": false,
  "ErrorPattern": "Expected loopback address but got:.*fe80::",
  "ExcludeConsoleLog": false
}

Note

🔒 Integrity filter blocked 2 items

The following items were blocked because they don't meet the GitHub integrity level.

• #114222 search_issues: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".
• #124716 search_pull_requests: has lower integrity than agent requires. The agent cannot read data with integrity below "approved".

To allow these resources, lower min-integrity in your GitHub frontmatter:

tools:
  github:
    min-integrity: approved  # merged | approved | unapproved | none

Generated by CI Outer-Loop Failure Scanner · ● 116.3M · ◷

Report

Build	Definition	Test	Pull Request
1420484	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution	#128068
1417637	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution	#128068
1416787	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution
1416322	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution	#128049
1415929	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution	#125437
1415126	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution
1414719	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution
1414320	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution
1396313	dotnet/runtime	System.Net.NameResolution.Functional.Tests.WorkItemExecution

Summary

24-Hour Hit Count	7-Day Hit Count	1-Month Count
0	1	9

[dotnet-policy-service]

Tagging subscribers to 'arch-android': @vitek-karas, @simonrozsival, @steveisok, @akoeplinger
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[dotnet-policy-service]

Tagging subscribers to this area: @karelz, @dotnet/ncl
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