CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [444]
Wireless
Every once in a while a technology comes along that, once the kinks are smoothed out, works flawlessly, creating a magical computing experience. Unfortunately, the various wireless networking technologies out there today don’t fulfill that dream yet. When they work, it’s like magic. You walk into a coffee shop, sit down, and flip open your laptop computer. After firing up your Internet browser, suddenly you’re quaffing lattes and surfing Web sites—with no wires at all.
Suffice it to say that connecting to the Internet via wireless means that you must connect to a cellular network or to a LAN that’s wired to an ISP. The local Internet café purchases high-speed Internet service from the cable or telecom company, for example, and then connects a wireless access point (WAP) to its network. When you walk in with your portable PC with wireless NIC and open a Web browser, the wireless NIC communicates with the fully wired DHCP server via the WAP and you’re surfing on the Internet. It appears magically wireless, but the LAN to ISP connection still uses wires.
Cellular networking is even more seamless. Anywhere you can connect with your cell phone, you can connect with your cellular network–aware portable or laptop computer.
Figure 25-21 A wiring closet
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NOTE One form of wireless communication does not require local wires. For Wireless broadband, the ISP must put up a tower, and then any building within the line of sight (perhaps up to 10 miles) can get a high-speed connection.
Satellite
Satellite connections to the Internet get the data beamed to a satellite dish on your house or office; a receiver handles the flow of data, eventually sending it through an Ethernet cable to the NIC in your PC. I can already sense people’s eyebrows raising. “Yeah, that’s the download connection. But what about the upload connection?” Very astute, me hearties! The early days of satellite required you to connect via a modem. You would upload at the slow 26- to 48-Kbps modem speed, but then get super-fast downloads from the dish. It worked, so why complain? You really can move to that shack on the side of the Himalayas to write the great Tibetan novel and still have DSLor cable-speed Internet connectivity. Sweet!
Satellite might be the most intriguing of all the technologies used to connect to the Internet today. As with satellite television, though, you need to have the satellite dish point at the satellites (toward the south if you live in the United States). The only significant issue to satellite is that the distance the signal must travel creates a small delay called the satellite latency. This latency is usually unnoticeable unless the signal degrades in foul weather such as rain and snow.
Windows Internet Connection Sharing
Internet Connection Sharing (ICS) enables one system to share its Internet connection with other systems on the network, providing a quick and easy method for multiple systems to use one Internet connection. Modern Windows versions (Windows 2000 through Windows 7) also provide this handy tool. Figure 25-22 shows a typical setup for ICS. Note the terminology used here. The PC that connects to the Internet and then shares that connection via ICS with other machines on a LAN is called the ICS host computer. PCs that connect via LAN to the ICS host computer are simply called client computers.
Figure 25-22 Typical ICS setup
To connect multiple computers to a single ICS host computer requires several things in place. First, the ICS host computer has to have a NIC dedicated to the internal connections. If you connect via dial-up, for example, the ICS host computer uses a modem to connect to the Internet. It also has a NIC that plugs into a switch. Other PCs on the LAN likewise connect to the switch. If you connect via some faster service, such as DSL that uses a NIC cabled to the DSL receiver, you’ll need a second NIC in the