NAC
Network access control checks a device before letting it onto the network: is it known, is it patched, is it running what it should be.
The idea is sound and the implementations have a reputation for being painful, because the failure mode is blocking legitimate people at inconvenient moments. It is also increasingly answering a question that matters less, now that being on the network is supposed to confer less trust in the first place.
Checked against the primary source.
