# Reverse zone network count should be retrievable

Understanding how many distinct networks have reverse lookup zones helps:

Source: https://maester.dev/docs/tests/AD-DNS-18

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

```powershell title="Run this check"
Invoke-Maester -TestId AD-DNS-18
```

## Overview

Understanding how many distinct networks have reverse lookup zones helps:

- **Network coverage assessment**: Ensure all internal networks have reverse DNS
- **IP space management**: Understand which networks are configured for reverse resolution
- **Security monitoring**: Identify gaps in reverse DNS coverage
- **Compliance verification**: Meet requirements for reverse DNS configuration

Each reverse zone represents a network segment that can be resolved from IP to hostname.

#### Control Type

**Operational**

#### Security Recommendation

- Maintain reverse zones for all production networks
- Ensure consistent coverage across the organization
- Document any networks intentionally without reverse zones
- Monitor for unauthorized reverse zone creation

#### How the Test Works

This test analyzes reverse lookup zone names to extract and count unique network addresses.

#### Related Tests

- `Test-MtAdDnsReverseZoneCount` - Counts reverse lookup zones
- `Test-MtAdDnsReverseZoneNetworkDetails` - Provides detailed network information

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-DNS-18 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | DNS |
| Area | Infrastructure hardening |
| Resource type | DnsZone |
| MITRE ATT&CK | None |
| PowerShell test | [Test-MtAdDnsReverseZoneNetworkCount](https://github.com/maester365/maester/blob/main/tests/ad/dns/Test.AD-DNS-18.ps1) |
| Services | ActiveDirectory |
| Permissions | ActiveDirectory:Remoting:Microsoft.PowerShell, ActiveDirectory:Cim:root\MicrosoftDNS:MicrosoftDNS_Zone:Read, ActiveDirectory:Cim:root\MicrosoftDNS:MicrosoftDNS_ResourceRecord:Read, ActiveDirectory:Cim:root\MicrosoftDNS:MicrosoftDNS_RootHints:Read |

</details>

## Source

- Test: [`tests/ad/dns/Test.AD-DNS-18.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/dns/Test.AD-DNS-18.ps1)
- Documentation: [`tests/ad/dns/Test.AD-DNS-18.md`](https://github.com/maester365/maester/blob/main/tests/ad/dns/Test.AD-DNS-18.md)