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Miguel Isidoro
Miguel Isidoro

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Pros and Cons of Single Tenant vs Multiple Tenants in Office 365

The post Pros and Cons of Single Tenant vs Multiple Tenants in Office 365 appeared first on Blog IT.

I recently was involved in a scenario with a customer that had to choose between having multiple Office 365 tenants or just a single tenant. This post will talk about some of the technical considerations that you will have to ask yourself if you are considering choosing between a single or a multi-tenant approach and the impacts that this decision has on the end user experience.


The decision of going with multiple tenants for your organization should not be taken lightly since it has a LOT of implications for the end user experience. I will discuss the end user experience implications in a greater detail below but let me be clear: you should choose to use a single Office 365 tenant for your organization if you can.

Common Scenarios for Multiple Tenants

There are a few scenarios that organizations may feel that the best or even the only option is to go with multiple tenants. Here are some of the most common scenarios:

  • Our organization is composed by several divisions worldwide and each division must have its data stored in different geographies
  • We must provide complete autonomy of administrative control for each division within the organization
  • We want to avoid network latency problems with Office 365 workloads (Ex: Exchange Online, SharePoint Online, Teams)
  • One of your divisions may one day leave the organization and we want to ensure that if this happens, data is properly isolated
  • The organization has multiple Office 365 licensing providers from different geographies

Going with multiple tenant is a possible way to solve the problems above but there are almost always alternative solutions. Recently, Multi-Geo capabilities were announced that allow organizations to split its data residency across different geographies without the need to have multiple tenants. To learn more about Multi-Geo Capabilities in Office 365, click here.

Important Technical Questions To Consider


One fairly common mistake that many organizations can make is to think that because they have multiple DNS domains, they need to have multiple Office 365 tenants. This is NOT true and you can have multiple domains in a single tenant (you can have up to 900 domains in a single Office 365 tenant, more details here).


In Office 365, users will authenticate to every workload using their identity, typically in one of the following scenarios:

  • An Azure Active Directory account synchronized with your local Active Directory environment (recommended scenario for most organizations)
  • A Cloud Only Account (if your organization doesn’t have a local Active Directory or some users will only need to access Office 365 and Cloud resources)

Azure Active Directory

If you need to sync your local Azure Active Directory with Azure Active Directory, there are a few considerations you have to take into account:

  • An Azure Active Directory tenant is associated to a single Office 365 tenant
  • Each user is unique in Azure Active Directory and you cannot synchronize the same user into multiple tenants. This has a very important implication: each user is a member of a single tenant and is consider as a Guest user in any other tenant
  • If you have multiple tenants, each DNS domain can only be registered in a single tenant
  • If you have a several local Active Directory forests and you want to sync all forests into a single tenant, you can only have one Azure AD Connect instance that will have to have access to all the local AD forests. To learn more about the Azure AD Connect supported topologies, click here

Tenant Migration

If you are in a case where there are already several tenants in your organization and you want to migrate users and Office 365 workloads into a single tenant, it is important to evaluate which workloads are already being used. The easiest migration path is if the only workload in use is email and the more workloads in use, the harder the migration will be.

If you still evaluating if you are going for a single tenant or multiple tenants, read on.

User Experience

One of the most important things to consider before deciding between a single or multiple tenants is the end user experience. Next, I will discuss in greater detail, what the end user experience will be like in each of the two scenarios.

To learn all about the Pros and Cons of Single Tenant vs Multiple Tenants in Office 365, click here.

Happy SharePointing!

The post Pros and Cons of Single Tenant vs Multiple Tenants in Office 365 appeared first on Blog IT.

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