The document details the classification of IP addresses into five classes (A to E) based on their first octet, along with their corresponding ranges, subnet masks, and the number of hosts and networks per class. It explains key concepts including priority bits for each class and the significance of network and broadcast addresses. Additionally, the document covers private IP address ranges and the purpose of subnet masks in determining network connectivity.

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 0 - 127 0xxxxxxx 0.0.0.0 – 127.255.255.255 255.0.0.0 224 - 2 27
Class B 128 - 191 10xxxxxx 128.0.0.0 – 191.255.255.255 255.255.0.0 216 - 2 214
Class C 192 - 223 110xxxxx 192.0.0.0 – 223.255.255.255 255.255.255.0 28 - 2 221
Class D 224 - 239 1110xxxx 224.0.0.0 – 239.255.255.255
Class E 240 - 255 1111xxxx 240.0.0.0 – 255.255.255.255

3. Five Different Classes
First Octet
decimal
(range)
First Octet
binary
(range)
IP range default
Subnet mask
Hosts Per
Network ID
(Usable
Addresses)
Number
Networ
0 - 127 0xxxxxxx 0.0.0.0 – 127.255.255.255 255.0.0.0 224 - 2
(16777214)
27-2
(126)
128 - 191 10xxxxxx 128.0.0.0 – 191.255.255.255 255.255.0.0 216
- 2
(65534)
214
-2
(16382)
192 - 223 110xxxxx 192.0.0.0 – 223.255.255.255 255.255.255.0 28
- 2
(254)
221
-2
(209715
224 - 239 1110xxxx 224.0.0.0 – 239.255.255.255
240 - 255 1111xxxx 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 0
• 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
= 28-1 (-1 is Priority Bit for Class A)
= 27
= 128 – 2 (-2 is for 0 & 127 Network)
= 126 Networks
• No. of Host
= 224
– 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
= 216
-2 (-2 is Priority Bit for Class B)
= 214
= 16384 Networks
• No. of Host
= 216
– 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
= 224
-3 (-3 is Priority Bit for Class C)
= 221
= 2097152 Networks
• No. of Host
=28
– 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