In this tutorial, you’ll learn how to monitor Active Directory health using PRTG Network Monitor.
This step-by-step guide focuses on basic SNMP monitoring for domain controllers.
Active Directory issues can impact user logins, authentication, and critical services.
PRTG allows IT administrators to detect AD problems early with real-time monitoring.
In this video, we demonstrate how to add a domain controller and configure SNMP sensors correctly.
You’ll also learn how to set alert thresholds for warning and critical states.
This tutorial is ideal for system administrators and network engineers.
Follow this guide to ensure your Active Directory environment stays healthy and reliable.

1. Enabling SNMP on AD

1️⃣ Install SNMP Service on Windows Server (DC)
Quick way (GUI)
Server Manager
Add Roles and Features
Next → Features
Tick: ✅ SNMP Service
(optional) SNMP WMI Provider
Install → reboot (recommended)

2️⃣ Configure SNMP Service (IMPORTANT)
Open Configuration
Services → SNMP Service → Properties
🔹 Tab: Security
1️⃣ Community
• Click Add
• Community name:

👉 Example: prtg_ro
• Permission:
o READ ONLY
❌ Absolutely DO NOT use public

2️⃣ Accepted community names
Only use the community you just created

3️⃣ Accept SNMP packets from these hosts
Select: ✅ Accept SNMP packets from these hosts
Add:IP PRTG Server
👉 Do not leave “Any” Host

🔹 Tab: Agent
Contact: IT
Location: DC01
Services: tick all

3️⃣ Open Firewall for SNMP
On DC: UDP 161

Limit Source IP, enter PRTG IP

2. Add device

Community name: prtg_ro

3. Add sensors

DC: 192.168.16.186

#1 Ping v2

DC cannot ping → everything is considered finished

#2. SNMP CPU Load

#3. SNMP Memory v2

Do not select Virtual Memory (pagefile)
Reason: Virtual Memory = pagefile → does not reflect DC status

#4. SNMP Disk Free v2

Warning: Almost out of space, few GB remaining

Threshold: Use Free Space (GB)

(Reason: % is very easy to be false, especially with different small/large disks)

#5. SNMP Traffic

SNMP Traffic is used to monitor network traffic (bandwidth) of the network card on the server/device.

SNMP Traffic helps you:

• Detect network congestion
• Determine if server slowdown is due to network issues
• Detect unusual traffic (backup, loop, malware, other VMs)

• Check for problems with NIC/switch/vSwitch

Ethernet – Connected – 4 GBit/s – Ethernet: This is the real NIC (or the main vNIC of the VM DC)
Ignore all disconnected states (default): Avoid downtime caused by virtual NICs turning on/off.

Show inbound and outbound traffic as positive and negative area graph: Very intuitive inbound/outbound view

Errors / Discards
Channel Warning Error
Errors In / Out >1 >5
Discards In / Out >1 >5

Normal AD is almost = 0
Total Traffic (4000 Mbps reported as false, actual card usage is 1000 Mbps)
Warning: >700 bandwidth (70% of 1 Gbps)

Down/Error: >900 bandwidth (≈ 90% of 1 Gbps)