How to view which network interface is connected to the network / Linux

If you have several network cards on your Linux-powered computer / server and need to determine which one is connected to the network, i.e. into which one the cable is plugged, command line, here is a simple command to find it out (this is something you might need when setting up your remote server):

$ ip link show

If it says NO-CARRIER, that means the cable is not connected to this network interface. In my case,  it's eth1:

eth1: <NO-CARRIER,BROADCAST,MULTICAST,UP>