Table 57 Allowed Ip Address Range By Class; Table 56 Classes Of Ip Addresses - Nortel 222 User Manual

262 Appendix G IP subnetting

Table 56 Classes of IP addresses

IP Address:
Class A 0
Class B 10
Class C 110
Therefore:
A class C network (8 host bits) can have 2
A class B address (16 host bits) can have 2
A class A address (24 host bits) can have 2
hosts).
Since the first octet of a class A IP address must contain a 0, the first octet of a
class A address can have a value of 0 to 127.
Similarly the first octet of a class B must begin with 10, therefore the first octet of
a class B address has a valid range of 128 to 191. The first octet of a class C
address begins with 110, and therefore has a range of 192 to 223.

Table 57 Allowed IP address range By class

Class Allowed Range of First Octet (Binary)
Class A 00000000 to 01111111
Class B 10000000 to 10111111
Class C 11000000 to 11011111
Class D 11100000 to 11101111
NN47922-501
Octet 1
Network number
Network number
Network number
Note: Host IDs of all zeros or all ones are not allowed.
Octet 2 Octet 3
Host ID Host ID
Network number Host ID
Network number Network number
8 –2 or 254 hosts.
16 –2 or 65 534 hosts.
24 –2 hosts (approximately 16 million
Allowed Range of First Octet (decimal)
0 to 127
128 to 191
192 to 223
224 to 239
Octet 4
Host ID
Host ID
Host ID