Installation guide

Appendix C TCP/IP Protocol 341
The following table summarizes the IP addressing scheme.
IP Address Criteria
Criteria
IP address
Class A
IP address
Class B
IP address
Class C
Maximum number of networks 127 16,384 2,097,152
Maximum number of
computers per network
16,777,214 65,534 254
Network number part First field First two
fields
First three
fields
Network number range 001–127 128.000–
191.255
192.000.000–
223.255.255
Node number part Last three
fields
Last two
fields
Last field
Node number range 000.000.001
–
255.255.254
000.001–
255.254
000–254
Subnet mask* 255.0.0.0 255.255.0.0 255.255.255.0
* If your network uses subnets, you must use the appropriate subnet mask. (This reduces
unnecessary network traffic.) If your network does not use subnets, then you must use
one of the values shown in the table.
For workstations, as you assign node numbers it is a good idea to begin
with the low end of the node number range and work up. Do not use 0
or 255 in a node assignment because these numbers are sometimes used
by TCP/IP.
Because IP addresses are unique, they must be assigned according to the
type and class of your network. If you plan to connect your network to
the DARPA Internet, you must get a DARPA Internet address. To get
an IP address, contact:
DDN Network Information Center SRI International Room EJ291
333 Ravenswood Avenue Menlo Park, CA 94025
If you have a private network, you do not need to get an IP address
from DDN.