for all LAN addressing, and all other address types are cross-referenced to it. A MAC
address is a 48-bit address that is expressed as 12 hexadecimal digits (4 bits to a hex digit).
Figure 20-11 shows the display from a WINIPCFG (Windows 98) command that includes
the MAC address (listed as the adapter address) of a NIC installed on a PC. The MAC
address of this PC is 44-45-53-54-00-00. The first three segments identify the manufacturer
and the remainder is a serial number for the NIC.
To display the MAC address on your Windows 98 PC, choose Start | Run and, in the
Open box, enter WINIPCFG and click OK.IP Addresses
Many LANS and virtually all WANs use IP (Internet Protocol) addresses to identify their
nodes. An IP address for a network workstation combines the address of the network and
the node into a 32-bit address that is expressed in four 8-bit octets (which means sets of
eight). Figure 20-12 shows the display of an IPCONFIG command that includes the IP
addressing information for a networked PC. IPCONFIG displays the IP address assigned
to the workstation (in this case, 192.168.1.100), its subnet mask (which is used to determine
how much of the address is used to designate the network or the node), and the default
gateway of the node.
IP addresses consist of four numbers separated by periods (dots). An IP address is 32 bits
long with each of the four numbers being eight bits long. The highest possible IP address
is 255.255.255.255, because the highest value that can be represented in eight bits is 255.
Each of the four numbers is called an octet, and they are referred to as the first, second,
third, and fourth octets.
IP addresses can be assigned as a static IP address (a fixed PC location) or as a dynam-
ically assigned IP address (changeable). A static IP address is permanently assigned to a
node when it is added to the network. Static IP addresses work as long as the network or
the node doesn’t change; for example, a static IP address would not work if a PC’s NIC
card changed or the network was reconfigured. Dynamic IP addresses are assigned eachChapter 20: Networks and Communications^527
Figure 20-11. The WINIPCFG command displays the MAC (Adapter) address of a PC’s NIC