This value is a running seconds counter that resets to zero every time snmpEngineBoots increments, so together the two numbers act as a clock for how long the current SNMP engine incarnation has been up. SNMPv3 authentication uses this timeliness value to reject old or replayed requests, so monitoring tools rarely read it directly but rely on it working correctly under the hood. For example, a value of 3600 means the SNMP engine has been running continuously for one hour since its last boot-counter increment.