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Class B Addresses
Nov 27,2008 00:00
by
alperen
Class B Addresses In a Class B address, the first two bytes are assigned to the network address, and the remaining two bytes are used for host addresses, by default. The format is Network.Network.Node.Node For example, in the IP address 172.16.30.56, the network address is 172.16, and the host address is 30.56. With a network address being two bytes of eight bits each, there would be 65,536 unique combinations. But the Internet designers decided that all Class B addresses should start with the two binary digits 10. This leaves 14 bit positions for IANA to manipulate; therefore, there are 16,384 unique Class B addresses. A Class B address uses two bytes for node addresses. This is 2 to the power of 16 minus the two reserved patterns (all 0s and all 1s in the host portion), for a total of 65,534 possible node addresses for each Class B network. Here is an example of how to find the valid hosts in a Class B network: 172.16.0.0 All host bits turned off is the network address. 172.16.255.255 All host bits turned on is the broadcast address. The valid hosts would be the numbers in between the network address and the broadcast address: 172.16.0.1 through 172.16.255.254. Just as you saw with Class A addresses, all Class B addresses have also been assigned. Many universities, which were connected to the Internet in the early 1990s, in addition to many bigname organizations such as Microsoft, Cisco, Sprint, Xerox, Novell, and Sun Microsystems, have all of these addresses consumed. However, they are available under the right circumstances. |