# DC operating system details should be retrievable

Understanding the operating system distribution across your domain controllers helps with:

Source: https://maester.dev/docs/tests/AD-DC-08

<!-- This file is generated by website/scripts/generate-test-docs.mjs. Do not edit manually. -->

<div class="test-byline"><div class="test-byline-avatars"><a class="test-byline-avatar test-byline-avatar--author" href="/contributors/soulemike" title="Michael Soule · Original author"><img src="https://github.com/soulemike.png" alt="Michael Soule" width="28" height="28" loading="lazy" decoding="async" /></a></div><div class="test-byline-meta"><span class="test-byline-text">Contributed by <a href="/contributors/soulemike">Michael Soule</a></span><a class="test-byline-link" href="/contributors">All contributors →</a></div></div>

<p class="test-part">Part of <a href="/docs/tests/ad">Active Directory</a> · Active Directory · Domain controllers · <a href="/docs/tests">All checks</a></p>

```powershell title="Run this check"
Invoke-Maester -TestId AD-DC-08
```

## Overview

Understanding the operating system distribution across your domain controllers helps with:

- **Security compliance**: Identifying DCs on unsupported OS versions
- **Patch management**: Planning update cycles across different OS versions
- **Upgrade planning**: Prioritizing which DCs to upgrade first
- **Capacity planning**: Understanding feature availability across DCs
- **Risk assessment**: Evaluating exposure from outdated systems

Domain controllers running end-of-life operating systems are a critical security risk as they no longer receive security updates, making them vulnerable to known exploits.

#### Control Type

**Operational**

#### Security Recommendation

**Upgrade domain controllers running end-of-life operating systems immediately.**

Priority order for upgrades:
1. Windows Server 2008 R2 and earlier (unsupported)
2. Windows Server 2012/2012 R2 (extended support ended)
3. Windows Server 2016 (still supported, but older)

Upgrade process:
1. Promote new DCs on supported OS versions
2. Transfer FSMO roles if needed
3. Demote old DCs
4. Remove from domain

#### How the Test Works

This test retrieves the OperatingSystem attribute from all domain controllers and groups them by OS version, showing:
- Count of DCs per OS version
- Percentage distribution
- Names of DCs running each OS

#### Related Tests

- `Test-MtAdDcOperatingSystemCount` - Count of unique OS versions
- `Test-MtAdDomainControllerCount` - Total DC count

#### Related links

- [Microsoft Learn: Windows Server release information](https://learn.microsoft.com/windows-server/get-started/windows-server-release-info)
- [ANSSI Active Directory checkpoints: DC/RODC with an obsolete operating system](https://www.cert.ssi.gouv.fr/uploads/ad_checklist.html#vuln_dc_obsolete)

## Details

<details>
<summary>Every attribute of this check</summary>

| Field | Value |
| --- | --- |
| Test ID | AD-DC-08 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Domain controllers |
| Area | Infrastructure hardening |
| Resource type | DomainController |
| MITRE ATT&CK | None |
| PowerShell test | [Test-MtAdDcOperatingSystemDetails](https://github.com/maester365/maester/blob/main/tests/ad/domain-controller/Test.AD-DC-08.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:nTDSDSA:ReadProperty |

</details>

## Source

- Test: [`tests/ad/domain-controller/Test.AD-DC-08.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/domain-controller/Test.AD-DC-08.ps1)
- Documentation: [`tests/ad/domain-controller/Test.AD-DC-08.md`](https://github.com/maester365/maester/blob/main/tests/ad/domain-controller/Test.AD-DC-08.md)