Networking Questions

ICMP is Internet Control Message Protocol, a network layer protocol of the TCP/IP suite used by hosts and gateways to send notification of datagram problems back to the sender. It uses the echo test / reply to test whether a destination is reachable and responding. It also handles both control and error messages.

It is the protocol the routers in neighboring autonomous systems use to identify the set of networks that can be reached within or via each autonomous system.

Along any transmission path from a given source to a given destination, a group of virtual circuits can be grouped together into what is called path.

It is a protocol used to advertise the set of networks that can be reached with in an autonomous system. BGP enables this information to be shared with the autonomous system. 

It is using a router to answer ARP requests. This will be done when the originating host believes that a destination is local, when in fact is lies beyond router.

The network layer concerns with the packets. It brings the packets from the source to the destination.

Virtual channel is normally a connection from one source to one destination, although multicast connections are also permitted. The other name for virtual channel is virtual circuit.

Hubs are specified or operate at Layer1 i.e, the physical layer in the OSI model. Hubs regenerate electrical signals. A hub sends data packets (frames) to all devices on a network, regardless of any MAC addresses contained in the data packet.