# Computer DNS zone count should be investigated

Security and Operational Insights: - Disjoint Namespaces: Multiple DNS zones may indicate disjoint namespace configurations - Multi-Domain Environments…

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

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

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

## Overview

- Understanding DNS zone distribution across domain computers helps identify network topology, disjoint namespace configurations, and potential DNS-related security issues.

**Security and Operational Insights:**
- **Disjoint Namespaces**: Multiple DNS zones may indicate disjoint namespace configurations
- **Multi-Domain Environments**: Helps understand domain and forest structure
- **DNS Security**: Identifies zones that need DNSSEC or other security measures
- **Network Segmentation**: May reveal network segmentation or perimeter boundaries

**Common Scenarios:**
- Single-domain environments typically have one DNS zone
- Multi-domain forests have multiple zones
- Disjoint namespaces require special configuration
- External DNS zones for perimeter networks

#### Control Type

**Operational**

#### Security Recommendation

1. **Validate Zone Configuration**:
   - Ensure all DNS zones are intentional and documented
   - Review disjoint namespace configurations
   - Verify DNS zone delegation is correct

2. **DNS Security**:
   - Enable DNSSEC for all DNS zones
   - Implement secure dynamic updates
   - Monitor for unauthorized zone transfers

3. **Documentation**:
   - Document all DNS zones and their purposes
   - Maintain network topology diagrams
   - Review during security audits

#### How the Test Works

This test extracts DNS zones from computer `dNSHostName` attributes and:
- Counts unique DNS zones
- Lists all zones in use
- Identifies computers without DNS host names

#### Related Tests

- `Test-MtAdComputerDnsHostNameCount` - DNS host name coverage
- `Test-MtAdComputerDnsZoneDetails` - Detailed zone breakdown
- `Test-MtAdDnsZoneCount` - DNS server zone analysis

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-DCOMP-08 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | Computers |
| Area | Infrastructure hardening |
| Resource type | DnsZone |
| MITRE ATT&CK | None |
| PowerShell test | [Test-MtAdComputerDnsZoneCount](https://github.com/maester365/maester/blob/main/tests/ad/security/Test.AD-DCOMP-08.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Ldap:computer:ReadProperty |

</details>

## Source

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