a is dum,
NIC is your Network Card. That is where you plug the CAT-5 Cable into the computer.
DHCP Server is something most Routers have that set the IP address for each computer on your network. (Without one, you have to manually set an IP Address for each computer on your network.)
IP like a unique ID set for each comp on your network so each comp can be identified for inbound and outbound data. (Like having a postal code.)
Take Care,
Richard