strange DHCP entries

Hello, little OT, but this is weird, on my DHCPserver i get a lot of these log entries: DHCPDISCOVER from 52:41:53:20:20:ea:a8:34:61:54:c0:01:01:00:00:00 via eth1 What kind of a MAC address is this supposed to be ? Any suggestions ? regards N. Dahlem