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How Routers Work

MAC Addresses

The chances are very good that you'll never see the MAC address for any of your equipment because the software that helps your computer communicate with a network takes care of matching the MAC address to a logical address. The logical address is what the network uses to pass information along to your computer.

If you'd like to see the MAC address and logical address used by the Internet Protocol (IP) for your Windows computer, you can run a small program that Microsoft provides. Go to the "Start" menu, click on "Run," and in the window that appears, type WINIPCFG (IPCONFIG/ALL for Windows 2000/XP). When the gray window appears, click on "More Info" and you'll get this sort of information:


Windows 98 IP Configuration:


DNS Servers:


Node Type: Broadcast

NetBIOS Scope ID:

IP Routing Enabled: Yes

WINS Proxy Enabled: No

NetBIOS Resolution Uses DNS: No

Ethernet adapter:

Description: PPP Adapter

Physical Address: 44-45-53-54-12-34

DHCP Enabled: Yes

IP Address:

Subnet Mask:

Default Gateway:

DHCP Server:

Primary WINS Server:

Secondary WINS Server: Lease Obtained: 01 01 80 12:00:00 AM

Lease Expires: 01 01 80 12:00:00 AM

There's a lot of information here that will vary depending on exactly how your connection to the Internet is established, but the physical address is the MAC address of the adapter queried by the program. The IP address is the logical address assigned to your connection by your ISP or network administrator. You'll see the addresses of other servers, including the DNS servers that keep track of all the names of Internet sites (so you can type "" rather than "") and the gateway server that you connect to in order to reach the Internet. When you've finished looking at the information, click OK. (Note: For security reasons, some of the information about this connection to the Internet has been changed. You should be very careful about giving your computer's information to other people -- with your address and the right tools, an unscrupulous person could, in some circumstances, gain access to your personal information and control your system through a "Trojan Horse" program.