NIC count different between CentOS 6 and CentOS 7

I’ve recently installed CentOS 7 over CentOS 6 Under CentOS 6 I had 6 (eth0 through eth5) physical NICs all working correctly After the CentOS 7 installation I now have only 5 physical NICs (enp3s0; enp5s4f0; enp5s4f1; enp5s6f0; enp5s6f1). What happened to the other one??? Under CentOS 6 the basic definitions could be found at /etc/udev/rules.d; where are they located under CentOS 7?