It can be anything! An apex, subdomain, or even a URL.
Results foractivedirectory.windowsazure.com.office.rp.skydemo.myshn.eu
www.activedirectory.windowsazure.com.office.rp.skydemo.myshn.euwindowsazure.com.office.rp.skydemo.myshn.eucom.office.rp.skydemo.myshn.euoffice.rp.skydemo.myshn.eurp.skydemo.myshn.euskydemo.myshn.eumyshn.eueu