# No replication connections should be disabled

Disabled replication connections in Active Directory can indicate several security and operational concerns:

Source: https://maester.dev/docs/tests/AD-REPL-01

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

```powershell title="Run this check"
Invoke-Maester -TestId AD-REPL-01
```

## Overview

Disabled replication connections in Active Directory can indicate several security and operational concerns:

- **Replication Failures**: Disabled connections may indicate failed or problematic replication between domain controllers
- **Incomplete Decommissioning**: Disabled connections from decommissioned DCs that weren't properly cleaned up
- **Attack Indicators**: Malicious actors may disable replication to prevent detection of changes made to the directory
- **Operational Risk**: Inconsistent directory data across domain controllers can lead to authentication failures and access control issues

Replication connections should normally be enabled to ensure consistent directory data across all domain controllers.

#### Control Type

**Detective**

#### Security Recommendation

- Regularly review disabled replication connections
- Investigate and resolve the root cause of disabled connections
- Remove connections for permanently decommissioned domain controllers
- Monitor for unexpected changes to replication connection status
- Document any intentionally disabled connections with business justification

#### How the Test Works

This test retrieves all Active Directory replication connections and counts:
- Total replication connections
- Disabled connections
- Enabled connections
- Percentage of disabled connections

#### Related Tests

- `Test-MtAdNonAutoReplicationConnectionCount` - Identifies manually created replication connections

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-REPL-01 |
| Severity | Low |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Replication |
| Area | Infrastructure hardening |
| Resource type | DomainController |
| User impact | Low |
| Implementation cost | Low |
| MITRE ATT&CK | None |
| PowerShell test | [Test-MtAdDisabledReplicationConnectionCount](https://github.com/maester365/maester/blob/main/tests/ad/replication/Test.AD-REPL-01.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:nTDSConnection:ReadProperty |

</details>

## Source

- Test: [`tests/ad/replication/Test.AD-REPL-01.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/replication/Test.AD-REPL-01.ps1)
- Documentation: [`tests/ad/replication/Test.AD-REPL-01.md`](https://github.com/maester365/maester/blob/main/tests/ad/replication/Test.AD-REPL-01.md)