Office 2021 Volume Activation: Complete KMS and MAK Setup Guide
If you're deploying Office 2021 across dozens, hundreds, or thousands of machines, you already know that manually entering product keys isn't practical. Volume activation exists to solve exactly this problem, and understanding how to set it up properly can save your IT team countless hours.
This guide walks through everything you need to know about activating Office 2021 in enterprise environments. We'll cover both Key Management Service (KMS) and Multiple Activation Key (MAK) methods in detail, including step-by-step setup instructions, configuration best practices, and troubleshooting tips.
Table of Contents
Understanding Volume Activation for Office 2021
Volume activation is Microsoft's system for activating products in bulk without requiring individual product keys on each machine. Instead of each computer needing its own unique retail key, volume activation lets you activate multiple installations using a single volume license key or through automated server-based activation.
Office 2021 supports three volume activation methods:
Key Management Service (KMS)
An on-premises server that activates Office installations within your network. Clients contact the KMS host periodically to maintain activation.
Multiple Activation Key (MAK)
A key that activates a predetermined number of machines directly with Microsoft. Each activation is one-time and permanent.
Active Directory-Based Activation (ADBA)
Uses Active Directory to automatically activate domain-joined computers. No separate activation infrastructure needed.
KMS vs MAK: Making the Right Choice
Both activation methods have their place. Understanding the tradeoffs helps you make the right decision for your organization.
| Factor | KMS | MAK |
|---|---|---|
| Activation Count | Unlimited (threshold-based) | Fixed limit per key |
| Internet Required | No (internal server) | Yes, for initial activation |
| Reactivation | Every 180 days automatically | One-time, permanent |
| Infrastructure | Requires KMS host server | No infrastructure needed |
| Minimum Devices | 5 for Office activation | No minimum |
| Ideal Scenario | Large, connected networks | Small deployments, isolated systems |
For most enterprises with centralized IT infrastructure, KMS is the preferred choice. Once set up, it handles activation automatically—no tracking spreadsheets, no running out of activations, no manual intervention.
MAK makes sense for edge cases: laptops that spend months offline, air-gapped systems, small branch offices, or test environments where KMS infrastructure isn't justified.
Setting Up a KMS Host Server
Setting up KMS requires a Windows Server that will act as the activation host. Here's how to get it running from scratch.
Prerequisites:
- Windows Server 2016, 2019, or 2022 (any edition)
- KMS host key from Volume Licensing Service Center (VLSC)
- Network connectivity to client machines
- DNS server for automatic KMS discovery (recommended)
- TCP port 1688 open in firewall
Step 1: Obtain Your KMS Host Key
Log into the Volume Licensing Service Center (VLSC) at microsoft.com/licensing/servicecenter. Navigate to Downloads and Keys, then search for "Office 2021" under your agreement. Download the KMS host key—this is different from product keys used on client machines.
Step 2: Install Volume Activation Services Role
# Using PowerShell (run as Administrator)
Install-WindowsFeature -Name VolumeActivation -IncludeManagementTools
# Or use Server Manager GUI:
# 1. Click "Add roles and features"
# 2. Select "Volume Activation Services"
# 3. Complete the wizardStep 3: Configure the KMS Host
- Select "Key Management Service (KMS)" as the activation type
- Enter your KMS host key from VLSC
- Activate the KMS host online (or by phone if disconnected)
- Configure optional settings like port number and DNS publishing
# Configure KMS via command line
cscript C:\Windows\System32\slmgr.vbs /ipk XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
cscript C:\Windows\System32\slmgr.vbs /ato
cscript C:\Windows\System32\slmgr.vbs /dlvStep 4: Configure DNS for Automatic Discovery
KMS clients can automatically find your KMS server through DNS SRV records. Create a DNS SRV record with these parameters:
Service: _vlmcs
Protocol: _tcp
Port: 1688
Host: kms-server.yourdomain.com
Priority: 0
Weight: 0Step 5: Verify KMS Host Is Working
# Check KMS host status
cscript C:\Windows\System32\slmgr.vbs /dlv
# Verify activation count
cscript C:\Windows\System32\slmgr.vbs /dli
# Check DNS SRV record
nslookup -type=srv _vlmcs._tcp.yourdomain.comConfiguring KMS Clients
With the KMS host running, client configuration is straightforward. Office 2021 volume editions automatically look for a KMS server.
Automatic Configuration (Recommended)
If DNS is configured correctly, Office 2021 volume installations will automatically discover and activate against your KMS server. No additional client configuration is needed.
<Configuration>
<Add OfficeClientEdition="64" Channel="PerpetualVL2021">
<Product ID="ProPlus2021Volume">
<Language ID="en-us" />
</Product>
</Add>
<Property Name="AUTOACTIVATE" Value="1" />
</Configuration>Manual KMS Server Configuration
# Navigate to Office installation folder
cd "C:\Program Files\Microsoft Office\Office16"
# Set KMS server address
cscript ospp.vbs /sethst:kms-server.yourdomain.com
# Set KMS port (if not default 1688)
cscript ospp.vbs /setprt:1688
# Trigger activation
cscript ospp.vbs /act
# Verify activation status
cscript ospp.vbs /dstatusMAK Activation Setup
MAK activation is simpler to set up but requires more careful management to avoid running out of activations.
Method 1: During Office Deployment
<Configuration>
<Add OfficeClientEdition="64" Channel="PerpetualVL2021">
<Product ID="ProPlus2021Volume" PIDKEY="XXXXX-XXXXX-XXXXX-XXXXX-XXXXX">
<Language ID="en-us" />
</Product>
</Add>
</Configuration>Method 2: After Installation (Command Line)
cd "C:\Program Files\Microsoft Office\Office16"
cscript ospp.vbs /inpkey:XXXXX-XXXXX-XXXXX-XXXXX-XXXXX
cscript ospp.vbs /act
cscript ospp.vbs /dstatusMethod 3: Phone Activation (Offline)
- Run: cscript ospp.vbs /dinstid (note the Installation ID)
- Call Microsoft activation center (number varies by region)
- Provide the Installation ID to the automated system
- Enter the Confirmation ID you receive
- Run: cscript ospp.vbs /actcid:CONFIRMATION-ID
Active Directory-Based Activation (ADBA)
ADBA is the simplest activation method for domain environments—it requires minimal ongoing management once configured.
ADBA stores activation objects in Active Directory. Domain-joined computers automatically activate when they connect to the domain.
Setup Steps:
- Install Volume Activation Services on a domain controller
- Select "Active Directory-Based Activation"
- Enter your KMS host key (same key used for KMS)
- Activate the key online
- Choose the AD forest and domain for the activation object
# Verify ADBA configuration
slmgr.vbs /dlv all
# On client machine, check activation method
cscript ospp.vbs /dstatusEssential Command Line Tools
Master these commands for managing Office 2021 activation:
OSPP.VBS - Office Software Protection Platform
# Location: C:\Program Files\Microsoft Office\Office16\ospp.vbs
cscript ospp.vbs /dstatus # View activation status
cscript ospp.vbs /dstatusall # View detailed status
cscript ospp.vbs /act # Activate Office
cscript ospp.vbs /inpkey:XXXXX # Install product key
cscript ospp.vbs /unpkey:LAST5 # Remove product key
cscript ospp.vbs /sethst:server # Set KMS host
cscript ospp.vbs /setprt:1688 # Set KMS port
cscript ospp.vbs /remhst # Clear KMS host setting
cscript ospp.vbs /dinstid # Display Installation ID
cscript ospp.vbs /actcid:ID # Enter Confirmation IDSLMGR.VBS - Software Licensing Manager
# Location: C:\Windows\System32\slmgr.vbs
cscript slmgr.vbs /dlv # View license status
cscript slmgr.vbs /dlv all # View all licenses
cscript slmgr.vbs /ipk XXXXX # Install product key
cscript slmgr.vbs /ato # Activate
cscript slmgr.vbs /skms server # Set KMS server
cscript slmgr.vbs /ckms # Clear KMS serverOffice 2021 Generic Volume License Keys (GVLKs)
GVLKs are used to configure Office 2021 clients for KMS activation. These are public keys provided by Microsoft:
| Product | GVLK |
|---|---|
| Office LTSC Professional Plus 2021 | FXYTK-NJJ8C-GB6DW-3DYQT-6F7TH |
| Office LTSC Standard 2021 | KDX7X-BNVR8-TXXGX-4Q7Y8-78VT3 |
| Project Professional 2021 | FTNWT-C6WBT-8HMGF-K9PRX-QV9H8 |
| Project Standard 2021 | J2JDC-NJCYY-9RGQ4-YXWMH-T3D4T |
| Visio LTSC Professional 2021 | KNH8D-FGHT4-T8RK3-CTDYJ-K2HT4 |
| Visio LTSC Standard 2021 | MJVNY-BYWPY-CWV6J-2RKRT-4M8QG |
| Access LTSC 2021 | WM8YG-YNGDD-4JHDC-PG3F4-FC4T4 |
| Excel LTSC 2021 | NWG3X-87C9K-TC7YY-BC2G7-G6RVC |
| Outlook LTSC 2021 | C9FM6-3N72F-HFJXB-TM3V9-T86R9 |
| PowerPoint LTSC 2021 | TY7XF-NFRBR-KJ44C-G83KF-GX27K |
| Publisher LTSC 2021 | 2MW9D-N4BXM-9VBPG-Q7W6M-KFBGQ |
| Skype for Business LTSC 2021 | HWCXN-K3WBT-WJBKY-R8BD9-XK29P |
| Word LTSC 2021 | TN8H9-M34D3-Y64V9-TR72V-X79KV |
Troubleshooting Common Issues
Even with proper setup, activation issues happen. Here's how to diagnose and fix the most common problems.
KMS Server Not Found
Client can't locate KMS host
- Verify DNS SRV record: nslookup -type=srv _vlmcs._tcp.domain.com
- Check firewall allows TCP port 1688
- Manually set KMS host: cscript ospp.vbs /sethst:server
- Ensure minimum 5 Office clients have contacted KMS
KMS Threshold Not Met
KMS requires 5 unique Office clients
- Deploy Office to at least 5 machines
- Run activation on each: cscript ospp.vbs /act
- Wait for threshold to be met
- All clients will activate once threshold is reached
MAK Activations Exhausted
Used all activations on MAK key
- Contact Microsoft licensing reseller for more activations
- Use VAMT proxy activation to reduce consumption
- Consider switching to KMS for larger deployments
Product Key Issues
Key doesn't work or wrong type
- Verify correct key type (GVLK for KMS, MAK for direct)
- Check key matches Office edition and version
- Remove existing keys: cscript ospp.vbs /unpkey:LAST5
- Reinstall correct key
Error 0xC004F074
No Key Management Service (KMS) could be contacted
- Verify KMS server is running and reachable
- Check network connectivity between client and KMS
- Ensure DNS SRV record is properly configured
- Temporarily try direct: cscript ospp.vbs /sethst:kms-server
Error 0x80070005
Access denied during activation
- Run Command Prompt as Administrator
- Check Windows firewall settings
- Verify user has proper permissions
- Disable antivirus temporarily and retry
Best Practices for Enterprise Activation
Use KMS for Primary Deployment
Provides automatic, unlimited activation with minimal management. Reserve MAK for edge cases.
Deploy Multiple KMS Hosts
For redundancy, run KMS on at least two servers. DNS round-robin provides automatic failover.
Document Your Configuration
Record KMS server names, DNS entries, and deployment procedures for future reference.
Monitor Activation Status
Use VAMT or scripted reports to track activation across your environment.
Secure Your Keys
Treat KMS host keys and MAK keys as sensitive credentials. Limit access appropriately.
Plan for Renewal
KMS clients reactivate every 180 days. Ensure KMS hosts remain accessible for ongoing activation.
Frequently Asked Questions
What is the minimum number of devices for KMS activation?
KMS requires a minimum of 5 unique Office clients to contact the KMS host before any activations will succeed. This is called the activation threshold.
How often do KMS clients need to reactivate?
KMS clients automatically reactivate every 180 days. If a client cannot reach the KMS host within 180 days, the activation will expire.
Can I use both KMS and MAK in the same environment?
Yes, you can use KMS for most devices and MAK for edge cases like disconnected or isolated systems. This is a common hybrid approach.
What happens if my KMS server goes offline?
Clients have a 30-day grace period. If the KMS server remains offline beyond 180 days from last activation, clients will enter reduced functionality mode.
Are GVLKs the same as product keys?
No. GVLKs (Generic Volume License Keys) only configure clients for KMS activation. They don't activate Office by themselves—you still need a KMS server.
Can I convert a retail license to volume license?
No, retail and volume licenses are separate. You cannot convert between them. You need to purchase the appropriate license type.