This question is very open because of many unknown variables.

It depends on the networking protocols (TCP/IP, Appletalk, etc...) you are using, Your chosen Network Medium (Wired, Wireless, Dial-up), the onboard port(S) that are holding the network cards, the network cards used and the network services (firewall, http, dhcp server, routing, etc...) that the computer is hosting.

The protocol, network medium, onboard ports, network cards and some network services are loaded through the kernel which can be checked using the lsmod command to see all running kernel modules. The other services can be tracked through your distros service management tools or you can reference them along with all other running apps by using the command ps -A