An Internet Protocol address (IP address) is a layer 3 logical address assigned by a network administrator. IP addresses are used to identify specific devices on a network.
An IP address is a 32-bit binary address usually written in dotted decimal formats. These 32 bits are further subdivided into four 8 bit segments called octets. Each octet is separated by a period.
AlsoRead: OSI Model 7 Layers Explained
Every IP address can be broken down into two main portions.
- Network Address Portion (Network ID)
- Host Address Portion (Host ID)
Network address portion is used to identify a specific network. Routers maintain routing tables that contain the network addresses. Host address portion is used to identify a specific endpoint on a network such as servers, printers, computers, mobile phones, etc… (Please Note – Routers build their routing tables based on network address not based on Host addresses.)
Address Classes/Classful Networks
This is a network addressing architecture used
This method divides IPv4 address space into five classes.
- Class A
- Class B
- Class C
- Class D
- Class E
These Address classes were determined and allocated by the Internet Assigned Numbers Authority (IANA)
In Class A addresses first bit of the first octet is always set to Zero.
00000000 – 01111111
Therefore in Class A addresses the first octet ranges from 0 – 127.
0.0.0.0 – 127.255.255.255
But 127 is reserved for loopback IP addresses. As an example, you can’t configure an IP address of 127.0.0.1 as a static IP on a PC. 0 is reserved for default network. So that can’t be used either to configure an IP address on a PC. As an example, you can’t configure an IP address
Because of the above-mentioned reasons the actual range of Class A
22.214.171.124 – 126.96.36.199
In a Class A Address the first 8 Bits denotes the Network Portion and the last 24 Bits denotes the Host Portion.
In Class B addresses first two bit of the first octet is always set to 10. (One and Zero).
10000000 – 10111111
Therefore in Class B addresses the first octet ranges from 128 – 191.
188.8.131.52 – 184.108.40.206
In a Class B Address the first 16 Bits denotes the Network Portion and the last 16 Bits denotes the Host Portion.
In the first octet of Class C addresses first 3 Bits are set to 110. (One One Zero)
11000000 – 11011111
Therefore in Class C addresses the first octet ranges from 192 – 223.
192.0.0.0 – 220.127.116.11
In a Class C Address the first 24 Bits denotes the Network Portion and the last 8 Bits denotes the Host Portion.
In Class D addresses the very first four bits of the first octet are set to 1110. (One One One and Zero)
11100000 – 11101111
Therefore in Class D addresses the first octet ranges from 224 – 239.
18.104.22.168 – 22.214.171.124
These addresses are reserved for Multi casting. In multi casting data is not transmit for a particular host. Therefore it’s not necessary to extract host address from the IP address.
Class E is reserved for experimental purposes.
In Class E addresses the very first four bits of the first octet are set to 1111. (One One One and One)
11110000 – 11111110
Therefore in Class E addresses the first octet ranges from 240 – 254.
240.0.0.0 – 254.255.255.254