Think of it like those old timey phone switch board operators. Incoming messages call a switch board. Then the operator or router helps divert traffic, sometimes the call stays inside your zip/area/lan other times it passes along to your isp to ask for help.
Think of it like those old timey phone switch board operators. Incoming messages call a switch board. Then the operator or router helps divert traffic, sometimes the call stays inside your zip/area/lan other times it passes along to your isp to ask for help.