96 CHAPTER 6 TCP/IP and Routing 10.0.0.0/8 Class A network address with the host ID range of 10.0.0.1 through 10.255.255.254. 172.16.0.0/12 Class B network address with a host ID range of 172.16.0.1 through 172.31.255.254. 192.168.0.0/16 Class C network address with the host ID range of 192.168.0.1 through 192.168.255.254. Another use of private addressing is called automatic private IP addressing (APIPA). If a computer running Windows 98 or later is configured to obtain its address automatically from a dynamic host configuration protocol (DHCP) server and it cannot locate a DHCP server, it will configure itself using APIPA. The computer randomly selects an address from the 169.254.0.0/16 address range and then checks the network for uniqueness. If the address is unique, it will use that address until it can reach a DHCP server. If the address is not unique, it will randomly select another address from that range. EXAM WARNING You must know the private address ranges as well as the APIPA IP address range for the Network+ exam. Also, do not forget the reserved loopback Class A address of 127.0.0.0. Considerations The private address blocks can be used in any network at any time. However, devices using these addresses will not be able to communicate with other hosts on the Internet without some kind of address translation. Some benefits of using private addresses are as follows: Number of addresses There are plenty of addresses for most internal networking needs. Security Private addresses are not routable on the Internet. The transla- tion from private to public addresses further obscures internal network information. Renumbering If using NAT, no readdressing of privately addressed networks is necessary to access public networks. Network design Treating private addresses as public addresses when allocating ensures that efficiency and design are maximized. STATIC AND DYNAMIC ASSIGNMENTS Static addressing Addressing configured by going to the physical location of a node or connecting through remote administration to configure a usable IP address. Dynamic addressing Addressing configured by a central server, which allocates and tracks the usage of IP addresses in the network.