We have been using Zabbix monitoring to monitor devices in automated fare collection in public transporting. We use zabbix trapper items mainly. Our devices are designed as offline solution so we have to keep items in device if zabbix server/proxy is not available and send them later in backgroud process on devices (just to keep history of device) asynchronously. We use both "clock" and "ns" parameters in items.

Now, let me introduce an example:

We have trigger with function last() on an item. If receive value =0 trigger should not fire. If receive value =1 trigger should fire. There is already last value =0 in history with timestamp 8:00. When server receive our old "offline" value =1 with timestamp 7:50 trigger is firing even if real last value is =0 based on timestamp.

Is this correct behavior of the last() function?