Hi there! Our deep scanning software, NEWT Pro, will show whether a PC or server is set to DHCP or Static. Having credentials is the one reliable method, but then you have non-PC devices that would be much more difficult to get the info directly, to the point of it not being worth it.
One could guess which devices are DHCP/static by repeatedly and continuously scanning and determining which devices move to other IPs or stay the same. This is something we'd like to add in v2.0 since automated/scheduled scanning is planned. Is that what you meant in your last suggestion?