What happens in the final step of adding my domain to Office 365?

If you chose, in the domains setup wizard, to have Office 365 operated by 21Vianet manage your DNS records, the final step in getting Office 365 set up with your domain name is to flip the switch by changing the nameserver (NS) records for your domain to point to the Office 365 nameservers. You make this change at your domain's domain registrar site. When you've done so and the changed NS records have updated through the DNS system, you're done! Your domain is set up with Office 365 services and ready to use.

Note:  To learn how you get started using your domain with Office 365, see Verify your domain in Office 365. We'll walk you through adding your domain to your Office 365 subscription, switching your user ID (which is also your email address) to use your domain name, and setting up your users' email addresses with your domain.

What happens when I update my NS records?

What exactly does this step do? In technical terms, changing your domain's NS records to point to another set of name servers is called redelegating your domain. Although your domain is redelegated to Office 365, the domain name is still registered with your domain registrar. You'll need to keep renewing your domain there. But because the domain is redelegated, Office 365 now manages your DNS records for you, including setting up your Office 365 services such as email and team sites.

When your NS records are updated across the DNS system, which typically happens quickly but can take up to 72 hours, email sent to your domain will start arriving at Office 365.

Important:  Please remember! Although you've configured your domain to work with Office 365 services, you can't let your domain expire by not paying your domain name registrar. If you don't renew your domain registration, your Office 365 services won't work. For example, email won't be delivered and Skype for Business Online won't work at all. Your domain name registrar provides you with information about your domain registration expiration.

How does updating NS records affect email?

Until you change your NS records, email addresses in Office 365 that use your domain name will still get email messages in their previous email system (for example, susan@fourthcoffee.com). Let people know when you're about to make the switch, so they'll go to Office 365 to find their email when it stops arriving in their current email system.

Just a reminder—be sure that you've added all the email addresses that use your domain to Office 365 before you switch over! What if you haven't added an email address that uses your domain name and you "flip the switch"—that is, change your domain's NS records to point to the Office 365 name servers? If you haven't added the email address to Office 365 first, any messages sent to that email address won't arrive. Not in the person's current email system and not in Office 365. So be sure to add all email addresses with your domain name to Office 365 before you flip the switch.

Do I have to update my NS records to Office 365?

You don't have to update your NS records if you'd rather keep managing your DNS records with the DNS hosting provider you're using now. The tradeoff is that you'll have to set up the DNS records for email, Lync, and so on for Office 365 yourself. If you switch your NS records to Office 365, the setup is taken care of for you.

If you decide to keep managing DNS yourself, check out these steps for setting up your own DNS records for Office 365 at a number of popular domain registrars.