Designing a highly available Exchange environment is not just in the hands of the messaging team, which unfortunately can be frustrating for some administrators or architects. Exchange is completely dependent on a variety of other services and systems that are usually administered and maintained by other teams. This chapter provides an overview of what should be done in order to improve the high availability of Active Directory, Domain Name System (DNS), network, storage, and virtualization platforms so that the likelihood of a failure with any of these systems causing an outage with Exchange is mitigated.