CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [407]
The client/server system dedicates one machine to act as a server, whose purpose is to serve up resources to the other machines on the network. These servers do not run Windows XP or Vista. They use highly sophisticated and expensive NOSs that are optimized for the sharing and administration of network resources. Dedicated server operating systems include Windows Server 2008, big UNIX systems such as IBM AIX and HP-UX, and some versions of Linux.
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NOTE The terms client and server are, to say the least, freely used in the Windows world. Keep in mind that a client generally refers to any process (or in this context, computer system) that can request a resource or service, and a server is any process (or system) that can fulfill the request.
Peer-to-Peer
Some networks do not require dedicated servers—every computer can perform both server and client functions. A peer-to-peer network enables any or all of the machines on the network to act as a server. Peer-to-peer networks are much cheaper than client/server networks because the software costs less and does not require that you purchase a high-end machine to act as the dedicated server. The most popular peer-to-peer NOSs today are the various versions of Windows and Macintosh OS X.
The biggest limiting factor to peer-to-peer networking is that it’s simply not designed for a large number of computers. Windows has a built-in limit (10) to the number of users who can concurrently access a shared file or folder. Microsoft recommends that peer-to-peer workgroups not exceed 15 PCs. Beyond that, creating a domain-based network makes more sense (see the following section).
Security is the other big weakness of peer-to-peer networks. Each system on a peer-to-peer network maintains its own security.
With the Windows Professional/Business versions, you can tighten security by setting NTFS permissions locally, but you are still required to place a local account on every system for any user who’s going to access resources. So even though you get better security in a Windows Professional/Business peer-to-peer network, system administration entails a lot of running around to individual systems to create and delete local users every time someone joins or leaves the workgroup. In a word: bleh.
Peer-to-peer workgroups are little more than a pretty way to organize systems to make navigating through Windows networks a little easier (Figure 23-14). In reality, workgroups have no security value. Still, if your networking needs are limited—such as a small home network—peer-to-peer networking is an easy and cheap solution.
Figure 23-14 Multiple workgroups in a network
Domain-Based
One of the similarities between the client/server network model and peer-to-peer networks is that each PC in the network maintains its own list of user accounts. If you want to access a server, you must log on. When only one server exists, the logon process takes only a second and works very well. The trouble comes when your network contains multiple servers. In that case, every time you access a different server, you must repeat the logon process (Figure 23-15). In larger networks containing many servers, this becomes a time-consuming nightmare not only for the user, but also for the network administrator.
Figure 23-15 Multiple logins in a peer-to-peer network
A domain-based network provides an excellent solution for the problem of multiple logins. In a domain-based environment, one or more dedicated servers called domain controllers hold the security database for all systems. This database holds a list of all users and passwords in the domain. When you log on to your