All Internet addresses are determined by a special organization called InterNIC, which administers the worldwide network. The existing IP addresses are divided into classes. The most common are classes A, B and C. Classes D and E are not intended for the end user.
Instructions
Step 1
The class of an IP address is determined by its first octet, i.e. the first numbers representing the values of each of the four bytes in decimal form. In general, any IP address is a combination of two logical parts:
- network number;
- node number in the network.
It is the first bits of the IP address that determine which part of such an address displays the network number and which part displays the node number on the network. Also, by default, each address class uses its own subnet mask.
Step 2
Class A networks have addresses starting from 0 to 126 and a subnet mask of 255.0.0.0. At the same time, number 127 is intended for special purposes, and number 0 is not used. An example of such an address is 10.52.36.11, where the octet is the number 10.
Step 3
The value of the first octet in the range from 128 to 191 indicates that the network belongs to class B. The subnet mask of such networks is 255.255.0.0. An example of such an address is 172.16.52.63, in which the number 172 is the first octet.
Step 4
If the IP address starts with a number in the range 192 to 223, then it is class C. Such addresses use a subnet mask of 255.255.255.0. An example of a class C address is 192.168.123.132, the first octet of which is 192.
Step 5
A single multicast address, or multicast, starting with 1110 is class D. Assigning a class D address to a packet address means that the packet is received by all hosts with that IP address. The subnet mask of class D addresses is 239.255.255.255.
Step 6
Another class of IP addresses reserved for future use is class E. The first digits of such addresses are the sequence 11110, and the subnet mask used by class E addresses is 247.255.255.255.
Step 7
Please note that in certain cases the subnet mask value may not meet the requirements of some organizations and may be reallocated.
