If you already have your own domain, you want to configure it to work with Office 365 operated by 21Vianet, and you want Office 365 to manage your DNS records for you, you need to do two things:
At your DNS host, confirm to Office 365 that you own the domain name.
At your domain registrar, change the domain nameserver records.
After you make these changes, Office 365 handles the rest of the required DNS changes and hosts your Office 365 DNS records.
Click a link for step-by-step instruction at these DNS hosts and domain registrars.
More options and things to be aware of:
If you don’t know the DNS hosting provider or domain registrar for your domain, find out how to locate your DNS services.
If your DNS hosting provider or domain registrar is not listed, learn how to verify your domain and change name servers at any DNS hosting provider or domain registrar.
If you like, you can manage your DNS records yourself at your DNS hosting provider instead of changing your nameservers to point to Office 365.