By themselves, computers are powerful tools. When they are connected in a network, they become even more powerful because the functions and tools that each computer provides can be shared with other computers. Networks exist for one major reason: to share information and resources Networks can be very simply, such as a small group of computers that share in information, of they can be very complex, spanning large geographical areas. Regardless of the type of network, a certain amount of maintenance is always required. Because each network is different and probably utilizes many diverse technologies, it is important to understand the fundamentals of networking and how networking components interact.
This chapter will introduce the components of a network and help you establish a based of knowledge that you can use throughout your networking studies, as well as help you prepare for the Network + certification exam.
In the computer would, the term network describes two or more connected computers that can share resources such as data, a printer, an Internet connection, application,s or a combination of these. In the following sections, we’ll discuss each type of network and describe the situation that is most appropriate for its use.
Local Area Network
By definition a local area network (LAN) is limited to a specific area, usually an office, and cannot extend beyond the boundaries of a single building. The first LANs were limited to a range (from a central point to the most distant computer) of 185 meters (about 600 feet) and no more than 30 computers. Today’s technology allows a larger LAN, but practical administration limitations require dividing it into small, logical areas called workgroups.
A workgroup is a collection of individual (a sales department, for example) who share the same files and databases over the LAN. Figure 1.1 shows an example of small LAN and its workgroups.
Wide Area Network
Chances are you are an experienced wide area network (WAN) user and don’t even know it. It you have ever connected to the Internet, you have used the largest WAN on the planet. A WAN is any network that crosses metropolitan, regional, or national boundaries. Most networking professionals define a WAN as any network that uses routers and public network links. The Internet fits both deifinitions.
WAN differ from LANs in the following ways:
- WANs cover greater distances.
- WAN speeds are slower.
- WAN can be connected on demand or permanently connected; LANs have permanent cannections between stations.
- CANs can use public or private network transports; LAN, primarily use private network transport.
- WANs can use either full-or half-duplex communications. LANs have typically used half-duplex communications, although many local area networks today use full-duplex communication (see the sidebar “Full-Duplex vs. Half-Duplex Communications”).
The Internet is actually a specific type of WAN. The Internet is a collection of networks that are interconnected and, therefore, is technically an internetwork (Internet is short for the word internetwork).
A WAN can be centralized or distributed. A centralized WAN consists of a central computer (at a central site) to which other computers and dumb terminals connect. The Internet, on the other hand, consists of many interconnected computers in many locations. Thus, it is a distributed WAN.
Host, Workstation, and Server
Networks are made up of lots of different components, but the three most common network entities are the host, workstation, and server. For the Network+exam, you need a good under-standing of these three primary components of a network. Each one of these items can be found on most networks.
In the classic sense, a workstation is a powerful computer used for drafting or other math-intensive applications. The term is also applied to a computer that has multiple central processing units (CPUs) available to users. In the network environment, the term workstation normally referes to any computer that is connected to the network and used by an individual to do work. It is important to distinguish between workstations and clients. A client is any network entity that can request resources from the network; a workstation is a computer that can request resources. Workstations can be clients, but not all clients, but not all clients are workstations. For example, a printer can reuest resources from the network, but it is a client, not a workstation.