CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [406]
Parallel/Serial
It would be unfair not to give at least a token nod to using the parallel or serial ports on a pair of PCs to make a direct cable connection. All versions of Windows have complete support for allowing two, and no more than two, systems to network together, using either parallel or serial cables. You need crossover versions of IEEE 1284 cables for parallel and RS-232 cables for serial. These should be considered only as a last resort option, given the incredibly slow speeds of parallel and especially serial cable transmission compared to that of Ethernet. You should never use direct cable connections unless no other viable alternative exists.
FireWire
You can connect two computers by using FireWire cables. Apple designed FireWire to be network aware, so the two machines will simply recognize each other and, assuming they’re configured to share files and folders, you’re up and running. See the section “Sharing and Security” later in this chapter for more details.
USB
You can also connect two computers by using USB, but it’s not quite as elegant as FireWire. The most common way is to plug a USB NIC into each PC and then run a UTP crossover cable between the Ethernet ports. You also can buy a special USB crossover cable to connect the two machines. Finally, at least one company makes a product that enables you to connect with a normal USB cable, called USB Duet.
Essentials/Practical Application
Network Operating Systems
At this point in the discussion of networking, you’ve covered two of the four main requirements for making a network work. Through Ethernet, you have a NIC for the PC that handles splitting data into packets and putting the packets back together at the destination PC. You’ve got a cabling standard to connect the NIC to a hub or switch, thus making that data transfer possible. Now it’s time to dive into the third and fourth requirements for a network. You need an operating system that can communicate with the hardware and with other networked PCs, and you need some sort of server machine to give out data or services. The third and fourth requirements are handled by a network operating system.
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EXAM TIP Both CompTIA A+ exams assume you have a working knowledge of network operating systems.
In a classic sense, a network operating system (NOS) is a portion of your operating system that communicates with the PC hardware and makes the connections among multiple machines on a network. The NOS enables one or more PCs to act as server machines and share data and services over a network—to share resources, in other words. You then need to run software on client computers so those computers can access the shared resources on the server machine.
Before you can share resources across a network, you must answer a number of questions. How do you make a resource available to share? Can everyone share his or her hard drives with everyone else? Should you place limits on sharing? If everyone needs access to a particular file, where will it be stored? What about security? Can anyone access the file? What if someone erases it accidentally? How are backups to be handled? Different versions of Windows answer these questions differently. Let’s look at network organization and then turn to protocols, client software, and server software.
Network Organization
All NOSs can be broken into three basic organizational groups: client/server, peer-to-peer, and domain-based. Let’s take a look at traditional network organization.
Client/Server
In a client/server network, one machine is dedicated as a resource to be shared over the network. This