Demystifying IP Addresses and Netmasks: The Complete Overview

In this blog, we will learn about IP addresses and netmasks.

IP

The Internet Protocol (IP) is a unique identifier for your device, similar to how a mobile number uniquely identifies your phone.

IP addresses are typically represented as four Octets for IPv4, with each octet being One byte/Octets in size, and eight octets for IPv6, with each octet being two bytes/Octets in size.

Examples:

• IPv4: 192.168.43.64
• IPv6: 2001:db8:3333:4444:5555:6666:7777:8888

For the purposes of this discussion, we will focus on IPv4.

Do we really require four Octets structure with dots between them?

The answer is NO

The only requirement for an IPv4 address is that it must be 4 bytes in size. However, it does not have to be written as four octets or even with dots separating them.

Let's test this by fetching Google's IP address using the nslookup command.

Convert this to binary number using bc calculator in Bash shell.

And you can see it’s working.

This is because the octet structure and the dots between them are only for human readability. Computers do not interpret dots; they just need an IP address that is 4 bytes in size, and that’s it.

The range for IPv4 addresses is from 0.0.0.0 to 255.255.255.255.

Types of IP Addresses

IP addresses are classified into two main types: Public IPs and Private IPs.

Private IP addresses are used for communication between local devices without connecting to the Internet. They are free to use and secure to use.

You can find your private IP address by using the ifconfig command

The private IP address ranges are as follows:

10.0.0.0 to 10.255.255.255
172.16.0.0 to 172.31.255.255
192.168.0.0 to 192.168.255.255

Public IP addresses are Internet-facing addresses provided by an Internet Service Provider (ISP). These addresses are used to access the internet and are not free.

By default

Private IP to Private IP communication is possible.
Public IP to Public IP communication is possible.

However:

Public IP to Private IP communication is not possible.
Private IP to Public IP communication is not possible.

Nevertheless, these types of communication can occur through Network Address Translation (NAT), which is typically used by your home router. This is why you can access the Internet even with a private IP address.

Netmasks
Netmasks are used to define the range of IP addresses within a network.

Which means,

You can see 24 Ones and 8 Zeros.

Here, we have converted 255 to binary using division method.

255 ÷ 2 = 127 remainder 1

127 ÷ 2 = 63 remainder 1

63 ÷ 2 = 31 remainder 1

31 ÷ 2 = 15 remainder 1

15 ÷ 2 = 7 remainder 1

7 ÷ 2 = 3 remainder 1

3 ÷ 2 = 1 remainder 1

1 ÷ 2 = 0 remainder 1

So, binary value of 255 is 11111111

By using this, we can able to find the number of IP addresses and its range.

Since we have 8 zeros, so

Number of IPs = 2 ^8 which equals to 256 IPs. SO, the usable IP range is 10.4.3.1 - 10.4.3.254 and the broadcast IP is 10.4.3.255.

And we can also write this as 255.255.255.0/24 . Here 24 denotes CIDR (Classless Inter-Domain Routing).

Thats it.

Kindly let me know in comments if you are any queries in these topics.