Today I saw this record in my log files:
dhcpd: DHCPDISCOVER from ff:ff:ff:ff:ff:ff via vlan400: network 184.108.40.206/24: no free leases dhcpd: DHCPDISCOVER from ff:ff:ff:ff:ff:ff via vlan300: network 100.100.120.0/24: no free leases
And so on, on all VLANs connected to the same ethernet card em1.
I am 99% sure that I have no devices on these VLANs which are able to send DHCP requests.
Also ff:ff:ff is a strange MAC.
So, my question is: is it something bad? Some errors on the ethernet-card or switch or something?