Whether you’re best served by using ExpressRoute to connect to a Microsoft cloud service depends on how Microsoft provides that service:
- Public internet-facing services like Microsoft 365, which uses Microsoft peering and publicly routable IP addresses.
- Services that run on the Azure platform, which use Azure private peering and private IP addresses.
Typically, we don’t recommend using ExpressRoute to connect to public internet-facing services like Microsoft 365. This echoes Microsoft’s advice; however there are occasional use cases where it is appropriate.
ExpressRoute is designed to connect your organisation to the Azure platform.