Through Microsoft Office 365, you have the ability to have Microsoft host your DNS entries.
This makes it easier to manage the entries required to get certain services working (aka Lync Online requires some interesting DNS records to be added and some DNS providers do not offer the ability to add the required SRV records)
In order to use Microsoft's DNS service, you need to point your domain namse servers to:
NS1 --> ns1.bdm.microsoftonline.com
NS2 --> ns2.bdm.microsoftonline.com