Serial interfaces do not pass any MAC information because the information is formed using WAN encapsulation (PPP. HDLC, Frame Relay).
When applying IPv4 addresses to router interfaces on a network, you would manually configure predictable addresses. For example, the lowest or highest address of the local subnet, on each particular router interface.
It depends on how many interfaces of router are connected to other networks. If a router is connected to two network, it will have 2 IP addresses. In a router having 4 ports it can connect to maximum 4 networks. In this case it will have 4 IP addresses.
Yes, in fact, every interface (or port) in the router must have not only a different IP address, but IP addresses in different networks, if those interfaces are to participate in IP routing.
"show interfaces" "show ip interface brief"
Show Interfaces
In modular router the interfaces are not fixed so that we will be able to installed cards latter on this router. But in case of non modular router the interfaces r fixed, we cannot able to add ports/interfaces latter on. That's all
The router ID is used to uniquely identify each router in the OSPF routing domain.If no loopback interfaces are configured, the router chooses the highest active IP address of any of its physical interfaces.
Configure the router ID on both routers. Configure the R2 router interfaces for area 0. Configure a loopback interface on both routers. Configure the proper subnet masks on the router interfaces.
A router may have multiple addresses depending on the number of interfaces to other networks. For a router to function effectively it must have at least 2 addresses, but some routers may have more.They Should only have one.
Boundary routers have interfaces in more than one major classful network.
Configure the R2 router interfaces for area 0.
In OSPF, interfaces can be assigned to different areas. Many times, a router will be routing inside of a major network, but different interfaces will belong to different areas. You need the level of control given by wildcard masks to assign different interfaces to their appropriate areas, and not restrict an entire major network to be in one area.