sysUpTime
sys Up Time
1.3.6.1.2.1.1.3
The time (in hundredths of a second) since the network management portion of the system was last re-initialized.
Back to rfc1213 MIB page.
IPHost Network monitor uses SNMP for monitoring health and availability of devices and applications in your network. You can send a SNMP Set to any remote device to monitor a specific SNMP object (CPU, Memory, Disk, Server Temperature, RAID failures, IO statistics, connection counts, error and much more).