Asset Management

Reverse DNS Lookup for investment managers and security professionals

Gijs Barends
  • over 1 year ago
  • 2 min read

A lesser-known product of is Reverse DNS Lookup. What is it and how can you leverage it?

With Reverse DNS Lookup you can find out what IP addresses (servers) are behind a domain name. For example: at the time of writing this piece the domain: returns a list of over 55 million IP addresses, all of which are individual servers from Amazon AWS.

An internet protocol (IP) address identifies a device on the internet. It is often compared to a phone number as it is unique and it allows sending and receiving data from a specific device. When you surf the internet with your computer, you are doing this with an IP address that your Internet Service Provider (ISP) assigned to you. An IP address like this can be personal identifiable information under privacy laws like the European General Data Protection Regulation (GDPR), meaning that they can be traced back to a person, including the browser history. At we don't collect these IP addresses.

However, a server that hosts a website also has an IP address. The most widely used IP addresses to date fall under Internet Protocol version 4 (IPv4) a naming convention established in the 1980s that writes IP addresses numerically, for example, There are around 4 billion IPv4 addresses and each month we scan all of them. We start with and then go up. We check what’s behind each IPv4 address. So we're interested to understand what machines are on the internet. This data is not considered personal identifiable information and cannot be traced back to an individual user.

Security professionals can use this data to get a full mapping of all IP addresses a client uses, including subdomains and VPNs.
Reverse DNS Lookup of how many servers does Amazon Web Services (AWS) have and how fast are they growing?

How can you leverage this data? This data may be of particular interest to security professionals and investment managers.

Security professionals can use this data to get a full mapping of all IP addresses a client uses, including subdomains and VPNs. To get security right, you need a complete overview of the web facing assets of a company. Especially with larger companies or institutions this is a challenge. Our Reverse DNS Lookup creates a comprehensive overview within second.

Investment managers want to understand a company they consider investing in as well as they can. When the company they want to invest in is relying on the web for a large part of their business, like cloud services, reverse DNS can be used to better understand how these companies are operating. For example: how many servers does Amazon Web Services (AWS) have? And because we do this month over month, we can also give a detailed picture of the trends over time and how fast a company's assets are growing.

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