Microsoft 365 requires connectivity to the Internet. The endpoints below should be reachable for customers using Microsoft 365 plans, including Government Community Cloud (GCC).
RSS feed of changes: https://endpoints.office.com/version/worldwide?allversions=true&format=rss&clientrequestid=b10c5ed1-bad1-445f-b386-b919946339a7
JSON configuration document: https://endpoints.office.com/endpoints/worldwide?clientrequestid=b10c5ed1-bad1-445f-b386-b919946339a7