An internet work is a collection of individual networks, connected
by intermediate networking devices, that functions as a single large
network. Internetworking refers to the industry, products, and
procedures that meet the challenge of creating and administering
internet works.

Major categories into which communications networks are classified

1. LAN
2. WAN
3. INTRANET
4. EXTRANET
5. INTERNET.

What is a LAN?

A LAN is a high-speed data network that covers a relatively small
geographic area. It typically connects workstations, personal computer,
printers, servers, and other devices. LANs offer computer users many
advantages, including shared access to devices and applications, file
exchange between connected users, and communication between users via
electronic mail and other applications.

LAN data transmissions fall into three classifications

1. unicast,
2. multicast, and
3. broadcast

In each type of transmission, a single packet is sent to one or more nodes.

In a unicast transmission, a single packet
is sent from the source to a destination on a network. First, the
source node addresses the packet by using the address of the
destination node. The package is then sent onto the network, and
finally, the network passes the packet to its destination.

A multicast transmission consists of a
single data packet that is copied and sent to a specific subset of
nodes on the network. First, the source node addresses the packet by
using a multicast address. The packet is then sent into the network,
which makes copies of the packet and sends a copy to each node that is
part of the multicast address.

A broadcast transmission consists of a
single data packet that is copied and sent to all nodes on the network.
In these types of transmissions, the source node addresses the packet
by using the broadcast address. The packet is then sent on to the
network, which makes copies of the packet and sends a copy to every
node on the network.