I'd like to put together a document for our junior technical staff on how to troubleshoot out of date definitions for a SEP client.

We have approximately 200 PCs running SEP with a single SEPM instance.  SEPM is configured to send email notifications when it detects out of date definitions on a SEP client.

What would everyone here in the community recommend as the very first thing to check after opening that email and seeing that "Computer A" has out of date definitions?  Besides the obvious such as "is it still on the network?"  We'll assume for these purposes that the computer is running, on the network, and all SEP services are started and running properly.  We'll also assume that the SEP client instance is still communicating properly with SEPM, and the green dot is present on the system tray icon.

Thanks for your help, everyone