# Reverse lookup zone count should be retrievable

Reverse lookup zones enable IP-to-name resolution (PTR records) and are essential for:

Source: https://maester.dev/docs/tests/AD-DNS-16

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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-16
```

## Overview

Reverse lookup zones enable IP-to-name resolution (PTR records) and are essential for:

- **Security auditing**: Identifying systems by IP address
- **Network troubleshooting**: Resolving IPs to hostnames
- **Application functionality**: Many services require reverse DNS
- **Compliance**: Some regulations require reverse DNS configuration

The number of reverse zones indicates network coverage for reverse resolution.

#### Control Type

**Operational**

#### Security Recommendation

- Maintain reverse zones for all internal networks
- Ensure reverse records are kept synchronized with forward records
- Protect reverse zones from unauthorized modification
- Monitor for unexpected changes to reverse zones

#### How the Test Works

This test counts reverse lookup zones (zones ending in .in-addr.arpa for IPv4 and .ip6.arpa for IPv6).

#### Related Tests

- `Test-MtAdDnsReverseZoneNetworkCount` - Counts distinct networks with reverse zones
- `Test-MtAdDnsReverseZoneNetworkDetails` - Provides detailed network information

## Details

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

| Field | Value |
| --- | --- |
| Test ID | AD-DNS-16 |
| Severity | Info |
| Suite | Active Directory |
| Product | Active Directory |
| Feature | DNS |
| Area | Infrastructure hardening |
| Resource type | DnsZone |
| MITRE ATT&CK | None |
| PowerShell test | [Test-MtAdDnsReverseZoneCount](https://github.com/maester365/maester/blob/main/tests/ad/dns/Test.AD-DNS-16.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-16.ps1`](https://github.com/maester365/maester/blob/main/tests/ad/dns/Test.AD-DNS-16.ps1)
- Documentation: [`tests/ad/dns/Test.AD-DNS-16.md`](https://github.com/maester365/maester/blob/main/tests/ad/dns/Test.AD-DNS-16.md)