What is an IP Address?
On the Internet, every connected device, from your laptop to the server hosting your favorite website, requires an address or Internet Protocol Address (IP address); without an IP address, devices would not be able to communicate with each other over the vast network that is the Internet.
These addresses are like digital postal codes, allowing data packets to be sent and received accurately and efficiently. So next time you browse the web or send an email, remember that it’s all made possible by the humble IP address.
This could be compared to houses in a city with house/flat numbers, street, and town names. The combination of these addresses enables a letter or parcel to find its way to the correct destination. In the same way, IP addresses serve as unique identifiers for devices connected to a network, allowing data packets to be routed to the correct destination. Just as a postal address includes specific components to ensure successful delivery, an IP address contains distinct parts that help facilitate communication between devices on the internet.
In the field of IPv4 (Internet Protocol version 4), addresses come in two main types: Public and Private.
Let’s look at what these terms mean and why they’re important in our interconnected world.
Understanding IPv4 Addresses
IPv4 addresses are 32-bit numbers typically shown as four decimal numbers separated by dots, like 192.168.1.1.
The 32 binary bits are broken into four octets (1 octet = 8 bits). Each octet is converted to decimal and separated by a period (dot). For this reason, an IP address is expressed in dotted decimal format e.g. 192.168.10.12.
The value in each octet ranges from 0 to 255 decimal, or 00000000 – 11111111 binary.
Below is how binary octets are converted to decimal: The right most bit, or least significant bit, of an octet, holds a value of 20.
The bit just to the left of that holds a value of 21. This continues until the left-most bit, or most significant bit, which holds a value of 27. So if all binary bits are 1s, the decimal equivalent would be 255 as shown here:
1 1 1 1 1 1 1 1
128 64 32 16 8 4 2 1 = (128+64+32+16+8+4+2+1=255)
And the sample below shows an IP address represented in binary and decimal.
192. 168. 4. 10 (decimal)
11000000.10101000.00000100.00001010 (binary).
Public vs. Private Addresses:
The core difference between public and private IPv4 addresses lies in their accessibility and usage on the internet.
Public IP Addresses:
Public IPs are accessible from anywhere on the internet. They are unique across the entire web, ensuring that data reaches the correct global destination.
These addresses are typically assigned to websites, external servers, and networks that need to be identified on the internet.
Internet Service Providers (ISPs) allocate public IP addresses. Due to the limited availability of IPv4 addresses, they are often dynamically assigned or shared through technologies like NAT (Network Address Translation).
Private IP Addresses:
Private IPs are used within local networks (like home or office networks) and are not routable on the wider internet.
This means they can’t be accessed directly from outside their local network.
Devices like your home computer, smartphone, and IoT devices often have private IP addresses.
These addresses facilitate communication within the same network without using a global, unique address.
Common private IP address ranges include 192.168.1.0, 10.1.0.0, and 172.16.1.0 to 172.31.0.0.
These ranges are set aside specifically for private use and are the same in networks worldwide.
Variable Lenght Subnet Mask (VLSM)
Classless interdomain Routing (CIDR)
Network Address Translation (NAT)
