Interactive Reports for Hosts - Availability 
Probably the most important metric for a host is its availability. You can use this report to display the development over time of the availability values for your administered hosts:
Host Availability ()
The report displays the availability of the chosen host. The availability is determined using an ICMP ping.
Note
For information about how you can specify the desired systems and the time interval to be displayed, and how to call interactive reporting, see Using Interactive Reporting.
For information about the different display options for the reports for hosts with regard to metrics and threshold values, see Interactive Reports for Hosts.