What Is the Sound of a Working Network?

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Figuring out whether a network is functioning is both easy and hard, and most observers, including novices and experts alike, agree that telling when a network's not working is easier than telling when it is! A client must know how to ask for services from the network and must state precisely what it's requesting. Likewise, a server must know how to recognize and evaluate incoming requests for its services and how to respond appropriately. Only then can a network work correctly.

Understanding how this constant stream of requests and replies works means looking a little deeper into how clients state their requests and how servers satisfy them. In the following sections, we examine the mechanics of this give-and-take.

Knowing how to ask is where the game begins

Knowing how to ask for network services requires some ability to distinguish between what's available locally on a client machine and what's available remotely from the network. Determining what's local and what's remote is the key to handling network access correctly. This determination depends on specialized software to handle the job in the background, so users don't necessarily have to know the difference.

A computer's main control program is called its operating system (OS) because it defines the software environment that lets a computer operate and run the applications and system services that get things accomplished on a machine. Most modern operating systems include built-in networking capabilities to augment their control over local resources and devices.

Certain modern operating systems can be called network operating systems (NOSs) when they create network server environments. Their built-in networking capabilities include a range of network services as part and parcel of the underlying operating system. Windows Server 2003 certainly fits this bill because it offers a broad range of powerful, flexible networking capabilities.

Right out of the box, Windows Server 2003 understands the differences between local and remote resources. The same is true for most modern desktop operating systems, including Windows XP Professional, Windows 2000 Server and Professional, Windows NT Server and Workstation, Windows 9 x , the Macintosh OS, as well as that old (but still modern) warhorse, UNIX.

KEY CONCEPT 

In Windows Server 2003, Windows XP Professional, Windows 2000, Windows NT, Windows 9 x , Macintosh, and UNIX operating systems, and through add-ons to DOS and Windows 3. x , a special piece of software known as a redirector keeps track of what's local and what's remote when users or applications request resources. The redirector takes generic requests for services and sends any that can't be satisfied locally to the appropriate service provider elsewhere on the network (in other words, to the appropriate server). Therefore, if you ask for a file that resides on a server elsewhere on the network, the redirector hands your request off to that machine and makes sure that the results of that request are delivered properly.

What's on today's menu?

For a computer to use network services, the computer must know how to ask for them. That's what a requester does. But knowing what to ask for is as important as knowing how to ask. In most cases, applications supply the necessary information about network services that they want to access, either through information supplied from a requester or through knowledge built directly into an application itself.

E-mail clients and Web browsers represent good examples of applications with sophisticated, built-in networking capabilities. On the other hand, file system access tools, such as Windows Explorer, My Computer, and My Documents, rely on the redirector to furnish them with views of (and access to) shared files and printers elsewhere on the network.

Please note that applications with built-in networking knowledge offer transparent access to network services because the applications know how to ask for services and, often, what to ask for on the user 's behalf . Programmers design such computer applications to be transparent to keep the applications out of sight and out of mind; therefore, the user remains blissfully unaware of cumbersome networking details and trivia. File managers, printer controls, and other tools with access to both local and remote resources, however, require users to be able to tell the difference between what's local and what's remote. In fact, such tools usually force users to request access to remote resources explicitly and directly.

Increasingly, finding out which services a network can provide is becoming more and more implicit. This is why all editions of Windows Server 2003 support a set of directory services to catalog and describe the services that the network can deliver to its users. Likewise, Windows Server 2003 support the Distributed File System that allows directories on multiple machines all around a network to appear as a single network drive to users. Therefore, users don't have to know where individual files or folders reside.

Such sophisticated mechanisms make it easier than ever before for users to request and access resources implicitly without having to know how to request those resources or having to determine exactly where they reside. Nevertheless, some explicit knowledge about such things is necessary if you want to make the most of Windows Server 2003's networking capabilities.

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Windows Server 2003 for Dummies
Windows Server 2003 for Dummies
ISBN: 0764516337
EAN: 2147483647
Year: 2003
Pages: 195

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