extranet
The main advantage of internal email is that it does not leave the organization's private network and thus is considered more secure. Internal email is often delivered more quickly as well because it stays in the private network.
In a Cisco borderless switched network design, the layer with more switches deployed than other layers is the Access layer. This layer connects end devices, such as computers and phones, to the network and typically requires a larger number of switches to accommodate the greater number of users and devices in a large organization.
Wide Area Network
yes, or more commonly known as LAN
DSLAM
WAN potentially, The Internet is a public network and a WAN (Wide Area Network) is usually private, either a leased line or a virtual private network (VPN) over the Internet.
Intranet – internal, private network using Web technologies to facilitate transmission of proprietary information within the organization. Extranet – two or more firms using the Internet to do business together.
More details are in related links area.
Routers connects different network to internet.There are 2 ways to connect to the internet.
Business communication is the process where information is exchanged:within a company or organizationfrom one company or organization to anotherfrom a private individual to a company or organizationfrom a company or organization to a private individualbetween two or more private individuals on a matter of business.
An intranet is a collection of private computer networks within an organization, while an extranet is a computer network that allows access from outside an organization. The prefixes "int" and "ext" mean inside and outside, respectively. The Internet is not directly related to the two, since it is a global system, while the other two are more localized network connections
Wide area network (WAN) that is usually a larger network that covers a large geographic area.