If you plan to use your trial tenant for production, be sure to choose a name for the tenant that is different from your planned production tenant name. It’s a common mistake to use a company name for the trial. The name of the tenant appears in Lync invites and SharePoint Online, but Microsoft does not currently have tools to rename a tenant or migrate data from one tenant to another. If you change your mind later, you have to create a new tenant and manually move your data and settings.

For example, you may want to name your tenant differently when setting up trial account as opposed to a production account

Please refer to : Get help with Office 365 domains

Please refer to this article in order to plan Network and Naming Services for Office 365

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