An IP address assigned by DHCP is only valid for X seconds (where X may be very short or very long or anything in between). So every DHCP client has a repeated need for communication on the network i.e. to renew the lease every X seconds (and in fact nearly all DHCP clients will start attempting to renew the lease substantially before the lease expires, in accordance with the DHCP RFC).
I do believe (someone correct me if I am wrong) that the exact behaviour is a relatively recent change (last few years).
- It used to be that there was nothing permanently sitting on the DHCP port (really the
- Nowadays there is something sitting on that port.
in either case as revealed by
Perhaps there was some reason for the change but I don’t know what it was.