# Schema version details should be retrievable

Comprehensive schema information provides the foundation for understanding your Active Directory infrastructure. The schema defines:

Source: https://maester.dev/docs/tests/AD-SCH-04

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<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 · Schema · <a href="/docs/tests">All checks</a></p>

```powershell title="Run this check"
Invoke-Maester -TestId AD-SCH-04
```

## Overview

Comprehensive schema information provides the foundation for understanding your Active Directory infrastructure. The schema defines:

- **Object classes**: What types of objects can exist (users, computers, groups)
- **Attributes**: What properties objects can have
- **Constraints**: Rules for object creation and modification

Understanding schema details helps with:
- **Troubleshooting**: Identifying schema-related issues
- **Planning**: Preparing for application deployments
- **Documentation**: Maintaining accurate AD documentation
- **Security**: Detecting unauthorized schema modifications

#### Control Type

**Operational**

#### Security Recommendation

Protect your schema with these practices:
- **Schema Admins group**: Keep membership minimal and monitored
- **Change control**: Require approval for all schema modifications
- **Documentation**: Maintain records of all schema extensions
- **Backup**: Regularly backup the schema NC (naming context)
- **Monitoring**: Alert on any schema modifications

#### How the Test Works

This test retrieves detailed information from the schema container including:
- Schema version number
- Corresponding Windows Server version
- Schema creation and modification dates
- Distribution of object classes
- Total schema object count

#### Related Tests

- `Test-MtAdSchemaVersionEntryCount` - Shows schema version number
- `Test-MtAdSchemaModificationYearCount` - Shows modification timeline
- `Test-MtAdSchemaModificationYearDetails` - Detailed modification breakdown

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-SCH-04 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Schema |
| Area | Infrastructure hardening |
| Resource type | Tenant |
| MITRE ATT&CK | None |
| PowerShell test | [Test-MtAdSchemaVersionDetails](https://github.com/maester365/maester/blob/main/tests/ad/schema/Test.AD-SCH-04.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:Schema/*.objectVersion:ReadProperty |

</details>

## Source

- Test: [`tests/ad/schema/Test.AD-SCH-04.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/schema/Test.AD-SCH-04.ps1)
- Documentation: [`tests/ad/schema/Test.AD-SCH-04.md`](https://github.com/maester365/maester/blob/main/tests/ad/schema/Test.AD-SCH-04.md)