Allowable Internet Addresses
893-743-A
F-3
Allowable Internet Addresses
Some Internet addresses are reserved for special uses and cannot be used for
host, subnet, or network addresses. Table F-1 lists ranges of Internet addresses
and shows which addresses are reserved and which are currently available.
Internet Address Conventions
If the bits in the host portion of an address are all 0, that address refers to the
network specified in the network portion of the address. For example, the Class
C address 192.31.7.0 refers to a particular network.
Conversely, if the bits in the network portion of an address are all 0, that
address refers to the host specified in the host portion of the address. For
example, the Class C address 0.0.0.234 refers to a particular host.
If the bits in the host portion of an address are all 1, that address refers to all
hosts on the network specified in the network portion of the address. For
example, the Class B address 128.1.255.255 refers to all hosts on the 128.1.0.0
network. (Remember that an octet of ones becomes the decimal number 255.)
Because of these conventions, do not use an Internet address with all zeros or
all ones in the host portion for your router address.
Table F-1. Reserved and available Internet addresses
Class
Address or Range
Status
A
0.0.0.0
Reserved
1.0.0.0 through 126.0.0.0
Available
127.0.0.0
Reserved
B
128.0.0.0
Reserved
128.1.0.0 through 191.254.0.0
Available
191.255.0.0
Reserved
C
192.0.0.0
Reserved
192.0.1.0 through 223.255.254
Available
223.255.255.0
Reserved
D, E
224.0.0.0 through 255.255.255.254
Reserved
255.255.255.255
Broadcast