Ask, what is the use of Serial interface?
I practiced on Tracker, some routers have this interface, some do not. Is this used to connect two routers?
I do not understand
There is another problem
G0/0, G0/1 two interfaces, the latter number represents the interface number, what does the preceding 0 mean?
Fa0/0/1 and Fa0/1/1, there are three numbers here. What do you mean by each?