It can be anything! An apex, subdomain, or even a URL.
Results for*.security.live.com.office.rp-microsofto365.federicodemo.myshn.eu
www.*.security.live.com.office.rp-microsofto365.federicodemo.myshn.eusecurity.live.com.office.rp-microsofto365.federicodemo.myshn.eulive.com.office.rp-microsofto365.federicodemo.myshn.eucom.office.rp-microsofto365.federicodemo.myshn.euoffice.rp-microsofto365.federicodemo.myshn.eurp-microsofto365.federicodemo.myshn.eufedericodemo.myshn.eumyshn.eueu