H

heartbeat

A group of packets that are sent over a private IP network between nodes to detect the health of the other nodes, as well as the health of the applications and services they manage within the cluster.

hosted organization

A collection of Exchange services including but not limited to virtual servers (that is, instances of IMAP4, SMTP, POP3, NNTP, HTTP, or RVP), storage space, and real-time collaboration facilities that exist to serve the needs of a single company. Internet service providers normally use a hosted organization to host multiple companies on the same physical computer. However, a hosted organization is not limited to a single Exchange server.