This chapter covers the deployment models for Microsoft 365 Apps, specifically the Click-to-Run (C2R) technology and the legacy Windows Installer (MSI) approach. Understanding these models is critical for the MS-900 exam, as questions on deployment methods, update channels, and licensing appear in approximately 10-15% of the exam. We will dissect how Click-to-Run works, its components, and how it differs from MSI, including practical configuration and troubleshooting.
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Imagine a restaurant chain with multiple branches. The head office decides on the menu and recipes. In the 'Click-to-Run' model, think of a food truck that arrives at each branch with pre-prepared, fully cooked meals in sealed containers. The branch just needs to unpack and serve — no cooking, no recipe adjustments. The food truck carries everything needed for a specific meal (like a specific Office version) and can be restocked from a central depot. In the 'MSI' model, each branch has a full kitchen with raw ingredients and a recipe book. They have to cook from scratch, which allows customizing ingredients (like customizing installation options), but it's slower, requires more skill, and every branch may end up with slightly different dishes. Updates in Click-to-Run are like the food truck bringing a new batch of pre-cooked meals — swap out the old containers. In MSI, updates mean the kitchen has to re-cook each dish, which takes time and can introduce inconsistencies. The restaurant chain prefers the food truck model for speed and consistency, but some branches (like corporate IT with strict compliance) may need the full kitchen to control every ingredient. Microsoft 365 Apps for enterprise uses Click-to-Run exclusively, while older perpetual Office versions used MSI.
What is Click-to-Run (C2R)?
Click-to-Run is Microsoft's streaming and virtualization technology for installing and updating Microsoft 365 Apps. It was introduced with Office 2013 and is the exclusive deployment method for Microsoft 365 Apps for enterprise (formerly Office 365 ProPlus). C2R uses a virtual application environment that isolates the Office applications from the underlying operating system, reducing conflicts with other software. The technology is based on Microsoft's App-V (Application Virtualization) technology, which streams application packages on demand.
Why C2R Exists
Traditional MSI-based installations required full download of all components, even if only a subset of features were needed. Updates were delivered as large service packs or security patches that could break customizations. C2R solves these problems by:
Streaming only the necessary bits to launch an application
Delivering updates as incremental delta changes (much smaller downloads)
Allowing multiple update channels (Monthly Enterprise, Semi-Annual, etc.)
Enabling faster installation (streaming vs. full copy)
How C2R Works Internally
C2R uses a combination of streaming, virtualization, and a local package cache. Here's the mechanism:
Streaming: When a user launches an Office app, C2R checks if the required components are already in the local cache. If not, it downloads only the necessary files from the Office Content Delivery Network (CDN) using Background Intelligent Transfer Service (BITS). The app can start before all components are downloaded (streaming).
Virtualization: C2R uses App-V technology to create a virtual environment for Office. This includes a virtual file system, registry, and process space. Office writes to these virtual locations instead of the real system, preventing conflicts with other applications.
Package Cache: All downloaded Office bits are stored in a local cache at %ProgramFiles%\Microsoft Office 15\root\vfs\ (or similar). The cache allows offline access and reduces re-downloads for repairs.
Update Mechanism: Updates are delivered as 'delta' packages that contain only the changed files. The C2R client downloads these deltas from the CDN and applies them to the cached package. This is much smaller than full MSI patches.
Key Components of C2R
- Office Deployment Tool (ODT): A command-line tool used to download, configure, and deploy C2R Office. It uses an XML configuration file to specify products, languages, update channels, and installation settings. - Office Content Delivery Network (CDN): The source for Office installation files and updates. Managed by Microsoft. - Update Channels: Define the frequency of feature and security updates. The exam focuses on: - Current Channel: Monthly feature updates (default for consumers) - Monthly Enterprise Channel: Monthly security updates, feature updates every 3 months (for enterprises) - Semi-Annual Enterprise Channel (Preview): Feature updates twice a year (preview release) - Semi-Annual Enterprise Channel: Feature updates twice a year (broad release) - Office Installation Files: The actual product bits, stored as a set of compressed files (.cab, .dat).
Configuration and Verification
To configure a C2R deployment using ODT:
Download ODT from Microsoft (setup.exe).
Create an XML configuration file (e.g., configuration.xml):
<Configuration>
<Add OfficeClientEdition="64" Channel="MonthlyEnterprise">
<Product ID="O365ProPlusRetail">
<Language ID="en-us" />
</Product>
</Add>
<Updates Enabled="TRUE" Channel="MonthlyEnterprise" />
<Display Level="None" AcceptEULA="TRUE" />
</Configuration>Run ODT in download mode to cache installation files locally:
setup.exe /download configuration.xmlDeploy to client machines:
setup.exe /configure configuration.xmlTo verify the installed version and update channel, use:
File > Account > About in any Office app (shows version and channel)
Registry: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\Configuration contains AudienceData and CDNBaseUrl.
Command line: cscript "%ProgramFiles%\Microsoft Office\Office16\ospp.vbs" /dstatus (shows license status)
Interaction with Related Technologies
Intune: Can deploy C2R Office via Intune using built-in Office 365 app deployment profile, which uses ODT under the hood.
Group Policy: C2R provides administrative templates (ADMX) for controlling update behavior, such as specifying update path, deadline, and source.
Microsoft 365 Apps Admin Center: Provides reporting on update status and allows configuring update channels centrally.
MSI Deployment Model (Legacy)
Before C2R, Office was deployed using Windows Installer (MSI). MSI packages are self-contained .msi files that install into Program Files. Updates are delivered as .msp patches. Key differences:
Installation: MSI requires full download of all components; C2R streams.
Updates: MSI patches are cumulative and can be large (hundreds of MB); C2R deltas are smaller.
Customization: MSI allows extensive customization via transforms (MST) and Setup Customization Tool; C2R uses ODT XML with limited options.
Virtualization: MSI writes directly to system; C2R uses App-V virtualization.
Licensing: MSI uses volume licensing (MAK/KMS); C2R uses subscription-based licensing (token-based).
Exam-Relevant Details
C2R is the only method for Microsoft 365 Apps for enterprise (subscription).
Update channels: Current, Monthly Enterprise, Semi-Annual Enterprise (Preview), Semi-Annual Enterprise.
Default channel for volume licensing: Semi-Annual Enterprise.
ODT is the primary tool for enterprise deployment.
C2R can be installed from local source or cloud CDN.
The exam may ask about the benefits of C2R: faster install, smaller updates, easier management.
Trap: C2R is not available for perpetual Office 2019/2021 (those use MSI for volume licensing, but Click-to-Run is also available for retail). Actually, Office 2019/2021 volume licensed uses MSI, but retail uses C2R. The exam may test that Microsoft 365 Apps for enterprise is C2R only.
Step-by-Step C2R Deployment
Download ODT: Obtain setup.exe from Microsoft (https://www.microsoft.com/en-us/download/details.aspx?id=49117).
Create XML Configuration: Define products, languages, update channel, and installation options.
Download Office Files: Run setup.exe /download config.xml to cache files locally or use CDN directly.
Install Office: Run setup.exe /configure config.xml on target machines.
Verify Installation: Check version and channel in Office app or registry.
Manage Updates: Use Group Policy or Intune to configure update settings.
Troubleshoot: Use ODT logging (/log switch) and check event logs for errors.
Download Office Deployment Tool
First, obtain the Office Deployment Tool (ODT) from the Microsoft Download Center. The tool is a single executable named `setup.exe`. This tool is the primary method for enterprise deployment of Click-to-Run Office. It supports downloading installation files from the Office CDN, configuring installation options, and deploying to client machines. Ensure you download the latest version to support the desired products and channels.
Create XML Configuration File
Create an XML file that specifies the products to install, languages, update channel, and installation settings. For example, to install Microsoft 365 Apps for enterprise (64-bit) with English language using Monthly Enterprise Channel, you would write a configuration like the one shown in the core explanation. The XML schema is defined by Microsoft and includes elements like `<Add>`, `<Product>`, `<Language>`, `<Updates>`, and `<Display>`. Common attributes: `OfficeClientEdition` (32 or 64), `Channel` (Current, MonthlyEnterprise, SemiAnnual), and `Version` (to pin a specific version).
Download Office Installation Files
Run `setup.exe /download configuration.xml` to download the Office installation files to a local network share. This step is optional; you can install directly from the CDN. However, downloading locally saves bandwidth and allows offline installation. The files are stored in a folder structure under the ODT directory. The download uses BITS to throttle bandwidth. The size of the download is approximately 2-3 GB per product. Ensure sufficient disk space and network capacity.
Install Office on Client Machines
Deploy Office by running `setup.exe /configure configuration.xml` on each client. This can be done via script, SCCM, Intune, or manually. The installer streams the required components to the local cache and creates virtualized application environments. Installation typically takes 10-20 minutes, depending on network speed and system performance. The `/configure` command respects the XML settings, such as disabling updates or removing previous versions.
Verify Installation and Update Channel
After installation, verify that the correct version and update channel are applied. Open any Office app (e.g., Word), go to File > Account, and check 'Office Updates' section. The channel is displayed. Alternatively, check the registry key `HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Office\ClickToRun\Configuration` for values like `AudienceData` (e.g., 'MonthlyEnterprise') and `CDNBaseUrl`. Also verify the product is activated by checking the license status using `ospp.vbs`.
Configure Update Settings via Group Policy
To manage updates centrally, import the Office ADMX templates and configure Group Policy settings. Key policies include: 'Update path' (specify internal update source), 'Update deadline' (force update by a date), 'Enable automatic updates', and 'Hide option to enable or disable updates'. These policies override the XML settings. For example, to set a deadline for Semi-Annual Channel updates, enable the policy 'Specify a deadline for updating Office' and set the date.
Troubleshoot Deployment Issues
If installation fails, check the ODT log file generated with the `/log` switch (e.g., `setup.exe /configure config.xml /log log.txt`). Common issues include: incorrect XML syntax, insufficient permissions, antivirus blocking, or network connectivity to CDN. Also check Windows Event Viewer under Application and System logs for Office-related errors. Use the Microsoft Support and Recovery Assistant (SaRA) for automated troubleshooting.
Enterprise Scenario 1: Large-Scale Deployment with Intune
A multinational corporation with 50,000 devices uses Intune to deploy Microsoft 365 Apps. They create an Intune profile for Office 365 (using the built-in Office 365 app deployment). Intune internally uses ODT but provides a simplified UI. The IT admin selects the suite (Microsoft 365 Apps for enterprise), update channel (Semi-Annual Enterprise), and languages. Intune pushes the installation to all managed Windows 10/11 devices. The challenge is bandwidth: downloading 2 GB per device from the CDN could saturate the internet link. To mitigate, they use Delivery Optimization (peer-to-peer caching) and configure a local update source using ODT's download feature. They also set update deadlines via Intune to ensure compliance. Common issue: devices not receiving updates because the Intune policy doesn't enforce the update channel correctly—solved by also applying a Group Policy for update path.
Enterprise Scenario 2: Offline Deployment in Air-Gapped Environment
A government agency with strict security policies requires all software to be installed from internal sources without internet access. They use ODT to download the full Office package for the Semi-Annual Enterprise Channel to a secure server. The download is done on a separate internet-connected machine, then transferred via USB drive. The XML configuration points the update source to an internal file share. They disable automatic updates via Group Policy and manually approve updates after testing. The challenge: keeping the offline source up-to-date. They schedule monthly downloads of the latest version from the CDN and test in a lab before deploying. Misconfiguration often occurs when the update path in the XML is incorrect, causing clients to fail to check for updates. They use the Office Admin Center to verify update status.
Enterprise Scenario 3: Hybrid Deployment with SCCM
A mid-size company uses System Center Configuration Manager (SCCM) to deploy Office. They create an application in SCCM using the ODT command line. The deployment type runs setup.exe /configure with a configuration file that specifies the Current Channel for early adopters and Semi-Annual for standard users. They use SCCM's distribution points to host the Office source files. Performance is good because SCCM uses BITS and peer caching. However, they encounter issues when users are on VPN: the update check fails because the client can't reach the internal update source. They resolve by configuring a fallback to the CDN via Group Policy. The key learning: always test XML configuration with the exact channel and version in a pilot group before broad deployment.
What MS-900 Tests on This Topic (Objective 4.1)
Objective 4.1: 'Describe Microsoft 365 Apps deployment models.' The exam expects you to:
Identify Click-to-Run as the exclusive deployment method for Microsoft 365 Apps for enterprise.
Compare Click-to-Run with MSI (Windows Installer) deployment.
Understand update channels: Current, Monthly Enterprise, Semi-Annual Enterprise (Preview), Semi-Annual Enterprise.
Know the Office Deployment Tool (ODT) is used to customize and deploy Click-to-Run.
Recognize that Click-to-Run uses streaming and virtualization.
Common Wrong Answers and Why
'MSI is used for Microsoft 365 Apps for enterprise.' Many candidates confuse perpetual Office with subscription. MSI is for volume licensed perpetual Office (2019, 2021). Microsoft 365 Apps for enterprise is C2R only.
'Click-to-Run does not support customization.' Candidates think because MSI allowed transforms, C2R lacks customization. In reality, ODT provides extensive customization via XML (products, languages, exclusions, updates).
'Updates are delivered as full packages in C2R.' The exam may test that C2R uses delta updates (only changed bits). MSI uses full patches. Candidates assume C2R is like MSI.
'Semi-Annual Enterprise Channel receives monthly feature updates.' The channel names are tricky. Semi-Annual receives feature updates twice a year, not monthly. Monthly Enterprise Channel gets monthly security updates but feature updates every 3 months.
Specific Numbers and Terms on the Exam
Update Channels: Current (monthly features), Monthly Enterprise (monthly security, quarterly features), Semi-Annual Enterprise Preview (2x year features, early), Semi-Annual Enterprise (2x year features, broad).
ODT: The tool name appears verbatim.
Streaming and Virtualization: Key benefits.
App-V: The underlying technology.
Delta updates: Smaller update size.
BITS: Background Intelligent Transfer Service for download.
Edge Cases and Exceptions
Office 2019/2021 Retail: These versions also use Click-to-Run! The exam may ask: 'Which deployment method is used for Office 2019 retail?' Answer: Click-to-Run. Only volume licensed perpetual uses MSI.
Mac: Microsoft 365 for Mac uses a similar technology but not called Click-to-Run; it uses Apple's installer with auto-update.
Office Online Server: Not applicable; that's server-based.
How to Eliminate Wrong Answers
If a question asks about deployment of Microsoft 365 Apps, eliminate any answer mentioning MSI, Windows Installer, or .msp patches. If it asks about customization, look for ODT. If it asks about update size, pick 'smaller' for C2R. If it asks about update frequency, match the channel name to its cadence.
Click-to-Run (C2R) is the exclusive deployment method for Microsoft 365 Apps for enterprise.
C2R uses App-V streaming and virtualization for faster installation and isolation.
Updates in C2R are delta (differential) packages, reducing download size.
The Office Deployment Tool (ODT) is used to customize and deploy C2R Office.
Update channels: Current (monthly features), Monthly Enterprise (monthly security, quarterly features), Semi-Annual Enterprise (2x year features).
Volume licensed perpetual Office (2019, 2021) uses MSI, not C2R.
C2R can be deployed offline by pre-downloading files using ODT /download.
Group Policy and Intune can manage C2R update settings centrally.
These come up on the exam all the time. Here's how to tell them apart.
Click-to-Run (C2R)
Uses streaming and virtualization (App-V)
Delta updates (smaller)
Exclusive to Microsoft 365 Apps for enterprise and retail perpetual
Deployed via ODT with XML configuration
Update channels: Current, Monthly Enterprise, Semi-Annual
Windows Installer (MSI)
Installs directly to file system
Full patch updates (MSP) – larger
Used for volume licensed perpetual Office (2019, 2021)
Deployed via MSI with MST transforms and SCCM
Updates via service packs or security patches
Mistake
Click-to-Run is the same as MSI but faster.
Correct
Click-to-Run uses streaming and virtualization via App-V, while MSI installs directly to the file system. C2R also uses delta updates, not full patches.
Mistake
All Office versions use Click-to-Run.
Correct
Only Microsoft 365 Apps for enterprise (subscription) and retail versions of Office 2019/2021 use Click-to-Run. Volume licensed perpetual Office 2019/2021 use MSI.
Mistake
Click-to-Run cannot be deployed without internet.
Correct
ODT can download installation files to a local share, enabling offline deployment. The /download command caches files locally.
Mistake
Semi-Annual Enterprise Channel gets monthly updates.
Correct
Semi-Annual Enterprise Channel receives feature updates twice a year. Security updates are monthly but delivered as part of the channel.
Mistake
Click-to-Run uses full package downloads for updates.
Correct
C2R uses delta (differential) updates that contain only changed files, making them much smaller than MSI patches.
Reveal each answer, then mark whether you got it right. Score 60%+ to unlock the next chapter.
Click-to-Run is Microsoft's streaming and virtualization technology for installing and updating Microsoft 365 Apps. It uses App-V to create a virtual environment, allowing faster installation and smaller updates via delta packages. It is the only deployment method for Microsoft 365 Apps for enterprise.
Use the Office Deployment Tool (ODT). Download setup.exe, create an XML configuration file specifying products, languages, and update channel, then run 'setup.exe /configure config.xml' on target machines. Optionally, pre-download files with 'setup.exe /download config.xml' for offline deployment.
Current Channel (monthly feature updates), Monthly Enterprise Channel (monthly security updates, quarterly features), Semi-Annual Enterprise Channel Preview (twice-yearly features, early release), and Semi-Annual Enterprise Channel (twice-yearly features, broad). The default for enterprises is Semi-Annual Enterprise.
No. Microsoft 365 Apps for enterprise (subscription) only supports Click-to-Run. MSI is only for volume licensed perpetual versions like Office 2019 or 2021.
Updates are delivered as delta (differential) packages that contain only the changed files. The C2R client downloads these from the Office CDN and applies them to the local package cache, resulting in smaller downloads compared to MSI patches.
The Office Deployment Tool (ODT) is a command-line tool (setup.exe) used to download, configure, and deploy Click-to-Run Office installations. It uses an XML configuration file to specify products, languages, update channels, and installation options.
Yes. You can use ODT with the /download switch to cache installation files to a local network share. Then deploy from that share using /configure without internet access.
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