Reverse IP Address Lookup

In this blog post we will try to introduce you to various concepts around IP, domains and how to find all domains that are on the same IP as some other domain A.

Then we discuss how to make a reverse IP address lookup.

Let us first look into what is IP address.

What is an IP address? An IP address is a unique number for computers, devices and servers connected to the internet. It’s like your home address on the global map of the internet. It helps everyone find you online. So if you want to reach your server, you have to type its IP address into your browser address bar. Each computer has its own unique IP address. The computer without IP is like an island without access to information in the rest of the world!

An IP address is comprised of four numbers in the range 0-255, separated by periods. Each portion of the IP address is known as an octet (or octad) – hence the term “dotted-decimal”.

IP addresses are the unique identifiers we use to send messages across the internet. They come in two flavors: IPv4 and IPv6.

Next, let us turn to domains.

What is domain name?

A domain name is a unique identity for internet users to access a certain server. For example, is the domain name used by the O’Reilly media company to publish books, magazines and digital materials. If you have such a requirement, then domain name registration may be suitable for you.

Dot-com domains like .com, .net, and .org are the original generic top-level domains (gTLDs), so they’re by far the most popular. But it’s not over yet! There are a whole new generation of domains called new gTLDs that you could still register today. New gTLDs are written in lowercase and have a wide range of purposes. Some of them relate to specific industries or professions like .healthcare, .law, and .architect. Others are broader terms, such as local communities or destinations, like .nyc, .earth, and .wales.

Having defined what IP addresses are and what domains are, let us now look into another question.

How to find out if there are other domains on the same address. This is what is called Reverse IP Address lookup.

There are many services which offer this. Usually they cover hundreds of millions of IPs.

Reverse IP lookups have many uses. They can be e.g. used to find groups of trending domains or products on the same network.