Rogue IP addresses in DHCP

[chrisjako]

noticed the network crashed yesterday after checking the logs on the server it was saying DHCP was full

 

I noticed a shed load of unique ID's all very similar, deleted them and everything went back to normal - this morning they have re-appeared

 

Can anyone advise on how to track this down? the logs give no help other then notifying me that DHCP is full

 

[sted]

they look like the elongated mac addresses ios devices can give if someone has multiple devices connected to one account. You could block those devices from getting a dhcp lease and see who complains?