A Device's "Last Seen" Timestamp Is Surprisingly Useful

Here's a very simple piece of data:

last_seen

That's it.

But it can tell you a lot.

If a device hasn't communicated for 30 seconds, maybe that's normal.

If it hasn't communicated for six hours, something might be wrong.

You can use it for basic device health monitoring:

if now - last_seen > timeout:
mark_device_offline()

Obviously, the timeout depends on the application.

A device that reports once per day shouldn't be considered broken after five minutes.

The nice thing about simple signals like this is that they don't require AI.

Sometimes a timestamp and a sensible rule are enough to solve a real problem.

Related resource: Aperture Venture Studio