In simple00coexistence, some users are provisioned in Office365, while the remaining users are provisioned in the onpremises environment. Both sets of users see the sameobjects in the GAL,and DirSync is used for GALsynchronization. Coexistence000 enables mail routing between onpremises and Office 365 using a shared DNS namespace, and email messages are routed between Office365 users and onpremises users, with the MXrecord pointing to either the onpremises environment or to Office365. Simple000coexistence does not require an onpremises HybridExchangeserver.