IP address and IP class - Computer Networking

ee classes of TCP/IP networks. Each class uses the 32-bit IP address space differently, providing more or fewer bits for the network part of the address. These classes are class A, class B, and class C.


Class A Network

This IP address class is used when there are a large number of hosts. In a Class A type of network, the first 8 bits (also called the first octet) identify the network, and the remaining have 24 bits for the host into that network.

An example of a Class A address is 102.168.212.226. Here, “102” helps you identify the network and 168.212.226 identify the host.

Class A addresses 127.0.0.0 to 127.255.255.255 cannot be used and is reserved for loopback and diagnostic functions.
Class B Network

In a B class IP address, the binary addresses start with 10. In this IP address, the class decimal number that can be between 128 to 191. The number 127 is reserved for loopback, which is used for internal testing on the local machine. The first 16 bits (known as two octets) help you identify the network. The other remaining 16 bits indicate the host within the network.

An example of Class B IP address is 168.212.226.204, where *168 212* identifies the network and *226.204* helps you identify the Hut network host.
Class C Network

Class C is a type of IP address that is used for the small network. In this class, three octets are used to indent the network. This IP ranges between 192 to 223.

In this type of network addressing method, the first two bits are set to be 1, and the third bit is set to 0, which makes the first 24 bits of the address them and the remaining bit as the host address. Mostly local area network used Class C IP address to connect with the network.

Example for a Class C IP address:

192.168.178.1
Class D Network

Class D addresses are only used for multicasting applications. Class D is never used for regular networking operations. This class addresses the first three bits set to “1” and their fourth bit set to use for “0”. Class D addresses are 32-bit network addresses. All the values within the range are used to identify multicast groups uniquely.

Therefore, there is no requirement to extract the host address from the IP address, so Class D does not have any subnet mask.

Example for a Class D IP address:

227.21.6.173
Class E Network

Class E IP address is defined by including the starting four network address bits as 1, which allows you two to incorporate addresses from 240.0.0.0 to 255.255.255.255. However, E class is reserved, and its usage is never defined. Therefore, many network implementations discard these addresses as undefined or illegal.

Example for a Class E IP address:

243.164.89.28

1. IP Address and IP class Presented By Md. Shohel Rana M.Sc in CSE KUET Head of CST - NUBNGPI

2. Five Different Classes Class First Octet decimal (range) First Octet binary (range) IP range default Subnet mask Number of Hosts Per Network ID Number of networks Class A - 127 xxxxxxx 0.0.0.0 – 127.255.255.255 255.0.0.0 - 2 Class B 128 - 191 10 xxxxxx 128.0.0.0 – 191.255.255.255 255.255.0.0 - 2 Class C 192 - 223 110 xxxxx 192.0.0.0 – 223.255.255.255 255.255.255.0 - 2 Class D 224 - 239 1110 xxxx 224.0.0.0 – 239.255.255.255 Class E 240 - 255 1111 xxxx 240.0.0.0 – 255.255.255.255 Class First Octet decimal (range) First Octet binary (range) IP range default Subnet mask Number of Hosts Per Network ID Number of networks Class A - 127 xxxxxxx 0.0.0.0 – 127.255.255.255 255.0.0.0 Class B 128 - 191 10 xxxxxx 128.0.0.0 – 191.255.255.255 255.255.0.0 Class C 192 - 223 110 xxxxx 192.0.0.0 – 223.255.255.255 255.255.255.0 Class D 224 - 239 1110 xxxx 224.0.0.0 – 239.255.255.255 Class E 240 - 255 1111 xxxx 240.0.0.0 – 255.255.255.255

3. Five Different Classes Class First Octet decimal (range) First Octet binary (range) IP range default Subnet mask Hosts Per Network ID (Usable Addresses) Number of Networks Class A - 127 xxxxxxx 0.0.0.0 – 127.255.255.255 255.0.0.0 - 2 (16777214) -2 (126) Class B 128 - 191 10 xxxxxx 128.0.0.0 – 191.255.255.255 255.255.0.0 - 2 (65534) -2 (16382) Class C 192 - 223 110 xxxxx 192.0.0.0 – 223.255.255.255 255.255.255.0 - 2 (254) -2 (2097150) Class D 224 - 239 1110 xxxx 224.0.0.0 – 239.255.255.255 Class E 240 - 255 1111 xxxx 240.0.0.0 – 255.255.255.255 Class First Octet decimal (range) First Octet binary (range) IP range default Subnet mask Hosts Per Network ID (Usable Addresses) Number of Networks Class A - 127 xxxxxxx 0.0.0.0 – 127.255.255.255 255.0.0.0 Class B 128 - 191 10 xxxxxx 128.0.0.0 – 191.255.255.255 255.255.0.0 Class C 192 - 223 110 xxxxx 192.0.0.0 – 223.255.255.255 255.255.255.0 Class D 224 - 239 1110 xxxx 224.0.0.0 – 239.255.255.255 Class E 240 - 255 1111 xxxx 240.0.0.0 – 255.255.255.255

4. Class D is reserved for Multicasting Class E is Reserved for future use, or Research and Development Purposes. Note: Class A addresses 127.0.0.0 to 127.255.255.255 cannot be used and is reserved for loopback and diagnostic functions.

5. Priority Bit Concept • To identify the range of each class a bit called priority bit is used. • Priority Bit is the left most bits in the First Octet • CLASS A priority bit is • CLASS B priority bit is 10 • CLASS C priority bit is 110 • CLASS D priority bit is 1110 • CLASS E priority bit is 1111

6. CLASS A Range For Class A range : First bit of the first octet should be reserved for the priority bit.

7. CLASS B Range For Class B range : First two bits of the first octet should be reserved for the priority bit.

8. CLASS C Range For Class C range : First Three bits of the first octet should be reserved for the priority bit.

9. CLASS D Range For Class D range : First four bits of the first octet should be reserved for the priority bit .

10. CLASS E Range For Class E range : First four bits of the first octet should be reserved for the priority bit.

11. Octet Format

12. Octet Format and subnet mask

13. No. Networks and Host formula

14. CLASS A – No. Networks and Host • Class A Octet Format is N . H . H . H • Network bits : 8 Host bits : 24 No. of Networks = -1 (-1 is Priority Bit for Class A) = = 128 – 2 (-2 is for 0 & 127 Network ) = 126 Networks • No. of Host = – 2 (-2 is for Network ID & Broadcast ID) = 16777216 - 2 = 16777214 Hosts/Network   CLASS A 126 Networks & 16777214 Hosts/ Nw CLASS A 126 Networks & 16777214 Hosts/ Nw

15. CLASS B – No. Networks & Host • Class A Octet Format is N . N . H . H • Network bits : 16 Host bits : 16 • No. of Networks = -2 (-2 is Priority Bit for Class B) = = 16384 Networks • No. of Host = – 2 (-2 is for Network ID & Broadcast ID) = 65536 - 2 = 65534 Hosts/Network   CLASS B 16384 Networks & 65534 Hosts/ Nw CLASS B 16384 Networks & 65534 Hosts/ Nw

16. CLASS C – No. Networks & Host • Class A Octet Format is N . N . N . H • Network bits : 24 Host bits : 8 • No. of Networks = -3 (-3 is Priority Bit for Class C) = = 2097152 Networks • No. of Host = – 2 (-2 is for Network ID & Broadcast ID) = 256 - 2 = 254 Hosts/Network   CLASS C 2097152 Networks & 254 Hosts/ Nw CLASS C 2097152 Networks & 254 Hosts/ Nw

17. Network & Broadcast Address • The network address is represented with all bits as ZERO in the host portion of the address • The broadcast address is represented with all bits as ONES in the host portion of the address • Valid IP Addresses lie between the Network Address and the Broadcast Address. • Only Valid IP Addresses are assigned to hosts/clients

18. Example and explanation- Class A

19. Example and explanation- Class B

20. Example and explanation- Class C

21. Private IP Addresses Class Private Networks Subnet Mask Address Range A 10.0.0.0 255.0.0.0 10.0.0.0 - 10.255.255.255 B 172.16.0.0 - 172.31.0.0 255.240.0.0 172.16.0.0 - 172.31.255.255 C 192.168.0.0 255.255.0.0 192.168.0.0 - 192.168.255.255

22. Every host on a network has IP address and subnet mask

23. Subnet mask Subnet mask is used by a computer to determine if another (target) computer is on the same network or on a different network. The function of a subnet mask is to determine whether an IP address exists on the local network or whether it must be routed outside the local network. Subnet mask is a 32-bit long string of 1’s followed by 0’s. Subnet mask looks like IP address .It is 32-bit long ,same length as IPv4 address.But they are different.

24. example Class c default subnet mask :255.255.255.0 in binary : 11111111.11111111.11111111.00000000 in shorthand : /24 Class B default subnet mask : 255.255.0.0 in binary : 11111111.11111111.00000000.00000000 in shorthand : /16 Class A default subnet mask : 255.0.0.0 in binary : 11111111.00000000.00000000.00000000 in shorthand : /8

25. /5 = 11111000.00000000.00000000.00000000 = 248.0.0.0 /20 = 11111111.11111111.11110000.00000000= 255.255.240.0 /25 = 11111111.11111111.11111111.10000000=255.255.255.128