The SNMP OID should get updated when the node is scanned, however, if it is part of a Provisioning Group it does NOT get updated. I have validated this with routers that we are swapping out. Our scan interval is set to 1d and they have been replaced for 1 week and the OID is the old string. I see the events where the scan completed each day. When I synchronize the group again the string gets updated.