ISDN service is an older (some say obsolete, but it won’t go away) technology but is still quite viable and is used by many businesses. It’s offered by many phone companies in some parts of the U.S. Instead of a modem, you use an ISDN adapter and a phone line with a special connection that allows the transmission and receipt of digital signals. ISDN offers data transfer rates of 57 Kbps and 128 Kbps. The telephone company must help you install the equipment.
Click here
for an ISDN Tutorial.
ISDN:
The “Obsolete” Dial-up Service That Won’t Go Away
PCGuide’s
Troubleshooting Modems Page
Excellent Modem Information
Site
What You Need
to Know About Modems
To identify a MAC Address, go to a DOS prompt. (If you’re on a Windows 95/98/ME computer, click Start, Run, and type WINIPCFG.) If on Windows NT/2000/XP, type IPCONFIG /ALL. What you’ll get is a screen that looks very much like this:
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The “Adapter Address” on the top line is the Media Access Control address on your NIC. This is unique throughout the world; no two devices ever have the same one. Manufacturers are assigned unique ranges of MAC addresses to burn into their products.
The MAC address on a computer’s NIC acts as the computer’s physical address (as opposed to the IP address, which is logical). It’s this address that a Layer 2 device, such as a bridge or a switch, uses to determine where to send data packets. You’ll also see the MAC address referred to as the “hardware address,” which makes sense because it’s permanently embedded in a piece of hardware, the NIC.
The address itself is a 12-digit hexadecimal number, which is represented by numbers 0 – 9 and the letters A – F. On the exam and elsewhere, look for MAC addresses to be displayed with colons, like this:
00:50:DA:C3:8A:F9
If you plan to seek other hardware certifications, like the CCNA, learn to count in hex. Two excellent hexadecimal tutorials are posted in Cramsession’s InfoCenter. You’ll find them here:
Binary
and Hexadecimal: One is the Loneliest Number
Counting
in Hexadecimal