Deploying Office Online Server (OOS) (Part 1)

If you would like to read the other parts in this article series please go to:


Office Online Server (OOS), currently in preview (not to be used in production! Keep an eye on Microsoft Exchange blog to get the information when this role is released for production environments), renders documents that can be viewed and edited using a variety of browsers and devices. This new Microsoft server role can be used with several other products, such as: SharePoint, OneDrive, Shared Folders and even web sites.

Office Online Server (OOS) has been around for a while in Microsoft Unified Messaging family, the former name was Office Web Apps (WAC) and that version could be used with Exchange Server 2013. However, starting with Exchange Server 2016, this server role got a special place because it is responsible for supporting the Modern Attachments feature.

That is cool, but why is it so important for Exchange Server 2016? Well it all boils down to a new feature called Modern Attachments, where Outlook Web App and Outlook 2016 clients are able to reference files instead of adding them as attachments to the messages, which at the end of the day saves a lot of space on the Mailbox Databases. A good example is a 10MB file attachment on the Mailbox Database, but starting on Exchange Server 2016 that will be just a link, and the end-user will be able to view/edit the file from the source without having the need to download it.

In this article series we are going over the process to deploy the Office Online Server and some tweaks to improve the product and how to configure Exchange Server 2016 to integrate with this server role.

Planning for Office Online Server (OOS) Server

In order to understand where we can install the Office Online Server, the easier way is to list all places where the server should not be installed. Basically, the server cannot be collocated with other server roles, such as: Domain Controllers, IIS, SharePoint, Exchange Server, Skype for Business Server and SQL Server. Also, we must not have Office client installed on the Office Online Server.

Long story short, to keep things simple and consistent, reserve a server just for the Office Online Server, and to make sure that you have a high available environment, the recommendation is to have a minimum of two (2) servers using a Load Balancing solution.

The Certificate is always a discussion topic on any design for Exchange and Skype for Business, and the same applies for Office Online Server. A good thing is that we can find synergies on all those products and they can share the same certificate if we plan well. Here are some recommendations that will help you to design your Office Online Server environment, as follows:

  • Use a Public Certificate (you can use SAN or wildcard certificates) although the preference is to use SAN (Subject Alternative Names)
  • Most likely you will use a Subject Alternative Name (SAN) certificate which will support several names, and for Exchange you can start as simple as 2 names to support a single site (you may need additional names based on your Disaster Recovery, or in case of having multiple sites)
  • Depending of your environment you can use the same Public Certificate for several services, such as SharePoint, Exchange Server, Skype for Business, Active Directory Federation Services, Office Online Server and so forth. Just keep adding names and it will be cheaper and it will reduce the hassle of maintaining several individual certs for each service/application.
  • Active Directory is able to resolve your public domain internally. If you have an invalid FQDN (e.g.: company.local) you may want to use a split-brain DNS where your public domain is created internally and the name resolution of that public zone internally is using internal servers.

Exchange Server 2016 and transition process

If you have been using WAC (Office Web Apps) with Exchange Server 2013, then we need to go over some details before introducing Office Online Server in your environment.

The main rule is about supportability. For starters, Exchange Server 2013 supports Office Web Apps (WAC) however it does not support Office Online Server (OOS), on the other hand Exchange Server 2016 supports Office Online Server (OOS) but it does not support Office Web Apps (WAC).

The take away of the planning is to make sure that you build a high available solution for Office Online Server (OOS), and that will avoid issues in case of a failure on the Office Online Server. We have a situation where Exchange Server 2016 tries to use an Office Web Apps (WAC) which is not a supported scenario.

DNS Configuration…

Active Directory may have a valid FQDN (Full qualified Domain Name), based on a TLD (top-level domain) name, such as,, or in some cases non-valid FQDN, such as company.local, company.corp. Since in this article we are working about the Office Online Server and Exchange Server 2016, and for both you should already have a deployed and stable Active Directory environment, so it is safe to say that the train has left the station when the subject is defining FQDN for your domain, so work with what you have.

Based on Microsoft’s recommendations it is easier to play with a valid FQDN when using products from Unified Communications family, such as: Skype for Business, Exchange Server and Office Online Server. There are a couple of reasons, one of the most compelling is that Public Certificates are issued only to valid FQDN, and in that case it is easier to point all Exchange Web Services to valid FQDN and use DNS (Internal and Public) to point the clients to the right server. Your current environment is in one of the situations below, so use the scenarios below to define where to configure your DNS to support Office Online Server.

  • If you have an invalid FQDN (e.g.: company.local, company.corp) you can create a valid FQDN zone at the DNS level (create as Primary Zone and store in Active Directory to guarantee the replication to all Domain Controllers), this format is also known as split-brain DNS. After creating the new zone that matches your valid FQDN, just add the names that will be used by Exchange Services, OOS, ADFS, and so forth as hosts on that new zone. I cover this entire process on this article.
  • If you already have a valid FQDN, then it is just matter of adding new entries for the new services that you defined on your certificate

Either way, you just need to create a new host (A or AAAA) using the defined Office Online Server name and in this article series we will be using as shown in Figure 01.

Figure 01

Deploying Office Online Server (OOS)

The process to install the Office Online Server requires a few software components and the following list has a summary of the required software and is using the proper installation order. We are going over each component in this section.

The first step is to install Windows Server features, and that can be done using the following cmdlet listed below (Figure 02). After installing those new features, a restart of the server is recommended before moving forward with the next step.

Install-WindowsFeature Web-Server, Web-Mgmt-Tools, Web-Mgmt-Console, Web-WebServer, Web-Common-Http, Web-Default-Doc, Web-Static-Content, Web-Performance, Web-Stat-Compression, Web-Dyn-Compression, Web-Security, Web-Filtering, Web-Windows-Auth, Web-App-Dev, Web-Net-Ext45, Web-Asp-Net45, Web-ISAPI-Ext, Web-ISAPI-Filter, Web-Includes, InkandHandwritingServices

Figure 02

The second step is to execute the Microsoft Visual C++ 2015 Redistributable (x64), and the installation process is straight forward. In the initial page (Figure 03), just select I agree to the license terms and conditions and click on Install.

Figure 03

After downloading the ISO file, double click on it and the content will be mounted on a drive letter of the server. Click on the new drive, and then on setup.exe that can be found on the root of that new drive (Figure 04)

Figure 04

In the initial page of the wizard, if you are in agreement with the license contract, select I accept the terms of this agreement and click on Continue.

In the second page, define the installation location which by default is C:\Program Files\Microsoft Office Web Apps and click on Install now to start the installation process, as shown in Figure 05.

Figure 05

The installation process is that simple, the final page should be similar to Figure 06 where the setup informs the administrator that the server has been installed, click on Close.

Figure 06

At this point we have the server installed but it is not fully functional, in the next article of our series we will be configuring the Public Certificate and assigning the DNS name that we defined on the Office Online Server.


In this first article we went over the initial requirement to install Office Online Server (OOS) and the installation of the product, in the next article of the series we will perform additional steps to configure the server.

If you would like to read the other parts in this article series please go to:

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