How to Add a Domain to an Office 365 Tenant

In this blog, we will discuss the process for adding a custom domain to Office 365 and other Microsoft cloud services. Ensure that you and your team are fully aware of any potential downtime and DNS propagation delays that may occur during this process.

What is a custom domain?

A custom domain name has your personal or company’s name. It can also include keywords that represent your site. It's your personal address, where anyone can find your website or online presence. For example, if you are running a company that provides dedicated servers, then your domain name could be Leasepacket.com. It directly informs everyone what kind of service you are offering. 

Prerequisites before adding a domain name to an Office 365 tenant

Before adding a domain name, first create a domain name with a domain registrar.

For an accredited domain registrar, see ICANN-Accredited Registrar. 

Create your directory:

       After you get your domain name, you can create your first directory. Sign in

       to the Azure portal for your directory, using an account with the owner role.  

       for the subscription. 

1. Create your new directory by following the steps in Create a new tenant for your organization.

The person who creates the tenant is automatically granted global administrator privileges. This role is highly privileged and can add additional administrators to the tenant.

2. For more information about subscription roles, see Azure Roles.

You must also register the domain name you choose for federation with your on-premises directory during the Microsoft Entra Domain step in the setup wizard. For details on this process, refer to the "Verify the domain selected for federation" guide.

How to Add a domain name to an Office 365 tenant?

1. After you create your directory, you can add your custom domain name.

2. Sign in to the Microsoft Entra admin centre as at least a domain name administrator.

3. Browse to Identity > Settings > Domain Names > Add a custom domain.

4. The unverified domain is added. The contoso.com page appears showing the DNS information needed to validate your domain ownership. Save this information.

Add your DNS information to the domain registrar.

5. Follow these steps:

• After adding your custom domain name, you'll need to go back to your domain registrar and enter the DNS information you copied in the previous step. Creating a TXT or MX record for your domain will verify that you own the domain name.

• Return to your domain registrar and create a new TXT or MX record for your domain using the DNS information you copied. Set the time to live (TTL) to 3600 seconds (60 minutes), and then save the record.

6. Verify your custom domain name.

             After you register your custom domain name, make sure it's valid in Microsoft Entra.   

             The propagation time can be instantaneous or it can take a few days, depending on

             your domain registrar.

       To verify your custom domain name, follow these steps:

1. Sign in to the Microsoft Entra admin center as at least a Domain Name Administrator.

2. Browse to Identity > Settings > Domain names.

3. In Custom domain names, select the custom domain name. In this example, select contoso.com.

4. On the contoso.com page, select Verify to make sure your custom domain is properly registered and is valid.

5. 

Common verification issues

If you are unable to validate a custom domain name, consider the following options:

• Before trying again, wait for at least one or two hours.  DNS records must propagate before you can verify the domain. This process can take an hour or more.

•  Verify that the DNS record is accurate. Return to the website of the domain name registrant. Make sure the entry is there, and that it matches the DNS entry information provided in the Microsoft Entra admin center.

• If you’re unable to update the record on the registrar’s site, share the entry with someone who has the necessary permissions to add it and verify its accuracy.

• Ensure that the domain name isn't already verified in another directory, as a domain name can only be verified in one directory at a time. If your domain name is currently verified in another directory, it cannot be verified in the new one. To resolve this issue, you'll need to delete the domain name from the old directory. For more information on deleting domain names, refer to the guide on managing custom domain names.

• Ensure that there are no unmanaged Power BI tenants within your organization. If any users have activated Power BI through self-service sign-up, creating an unmanaged tenant, you’ll need to take over its management. This can be done as an internal or external admin using PowerShell. For more details, see the guide on taking over an unmanaged directory.   

Conclusion 

In this blog, we covered how to add a domain to your Office 365 tenant. Start by going to the settings in the Microsoft 365 admin portal and adding the domain. After verifying the domain with the TXT value, proceed with the setup. 

At the final step, you’ll be presented with several DNS records. Avoid adding these records to your DNS host immediately, as doing so could cause mail flow issues in production. Safely close the wizard and disregard any status information or warnings about the domain.

FAQs

Q1. How long does it take to verify a domain in Office 365?

Verification typically takes a few minutes, but DNS propagation can sometimes delay the process. It may take up to 24–48 hours for the changes to fully propagate across the internet.

Q2. What happens if I accidentally add the DNS records too early?

Adding DNS records too early can lead to mail flow issues and disrupt services. If this happens, revert the changes to your DNS host and ensure proper planning before reapplying the records.

3. Can I add multiple domains to a single Office 365 tenant? 

Yes, you can add multiple domains to a single Office 365 tenant. This allows you to manage email addresses and services across different domains within the same organization.