This post may contain affiliate links, please read our affiliate disclosure to learn more.
WHOIS: How to Use WHOIS for Security Investigations?

WHOIS: How to Use WHOIS for Security Investigations?

 By Charles Joseph | Cybersecurity Researcher
 Published on August 7th, 2023
This post was updated on November 25th, 2023

WHOIS is a protocol that’s used to query databases to obtain information about the registration of a domain name or an IP address. It’s like an internet ‘phone book’ that provides ownership details, including the person or organization that owns the domain, their contact details, and when it was registered or was due to expire.

How Does WHOIS Work?

The whois protocol queries databases for information on domain names, IP addresses, and more.

Stay One Step Ahead of Cyber Threats

Want to Be the Smartest Guy in the Room? Get the Latest Cybersecurity News and Insights.
We respect your privacy and you can unsubscribe anytime.

When you make a whois request, the client software sends a query to a specific whois server based on the domain’s top-level domain (TLD) or IP range.

Each TLD and regional internet registry has its own designated whois server. If the initial server doesn’t have complete data, it can refer the query to another server.

The whois server then responds with the requested details, such as registrant information, domain dates, and nameservers.

The client displays this information to the user.

Due to privacy concerns, some data might be masked or limited. Services like “WhoisGuard” offer protection by replacing personal data with proxy information.

How to Use the WHOIS Command

It’s really easy to use the WHOIS command. Below are examples for Windows and Linux.

On Windows:

  1. Open Command Prompt or PowerShell.
  2. Run the command:

On Linux:

  1. Open your terminal.
  2. Run the command:

In both examples, replace with the domain you wish to query.

If you’d prefer to use the internet, kindly visit the website and type your domain there for results.

WHOIS Examples

1. Domain Availability and Expiry Date

Imagine you’re planning to launch a new website. You have the perfect domain name that fits your business or project. Before getting your hopes up, you need to check if this domain is available. This is when WHOIS comes into play.

By entering your chosen domain name into a WHOIS lookup tool, you can quickly discover if it’s already owned by someone else. If it is registered, the tool will provide the registration and expiry date. If the domain expires soon, you might be able to acquire it if the current owner decides not to renew their registration.

This information is crucial in your strategic planning for your website launch. It aids in identifying your next steps, whether that means brainstorming a new domain name, preparing to negotiate with the current domain owner, or patiently waiting for the potential expiry.

2. Identifying Website Ownership

Let’s say you come across a website that has caught your attention, and you’re keen to know who’s behind it, whether it’s a competitor or a potential collaborator. WHOIS is your go-to tool.

You can perform a WHOIS lookup and find out who owns the domain of that intriguing website. This isn’t limited to just names but includes contact information like an email address or phone number, provided the owner hasn’t chosen to hide these details.

This access to ownership information can prove useful in various scenarios. For instance, if you’re impressed with the website and want to collaborate, you can use the contact details to reach out. On the contrary, if there’s content that shouldn’t be there or is incorrect, you can bring it to the owner’s attention.

3. Investigating Suspicious Emails

Imagine you’re receiving emails from an unknown domain. The emails could be spam, or, worse, phishing attempts. In such scenarios, WHOIS can be a valuable tool for your investigation.

You can identify who owns this domain by performing a WHOIS search on the domain from which the emails are coming. This can either confirm your suspicion or assuage your concerns.

The information gathered from the search can also be useful if you need to report fraudulent activities. Providing this data to your email service provider or the authorities can significantly resolve the issue and protect others from similar threats.


In essence, WHOIS is an indispensable tool that allows us to gather essential information about a domain name or an IP address. Whether we want to purchase a domain, understand website ownership, or investigate suspicious emails, a WHOIS lookup can provide key details to make informed decisions.

Key Takeaways

  • WHOIS is an internet protocol used to look up information related to domain names and IP addresses.
  • You can use WHOIS to check domain availability and expiry dates, providing crucial data for strategic planning for a website launch.
  • WHOIS helps to identify website ownership, offering insights about potential collaboration or competition.
  • Investigating suspicious emails can be done using WHOIS, as it reveals the owner of the domain from where the emails are coming from.
  • WHOIS is an important tool for cybersecurity and data investigations.

Related Questions

1. Can WHOIS help me find out how old a website is?

Yes, by checking the registration date via a WHOIS lookup, you can find out when a website was launched.

2. Is WHOIS information always accurate?

Mostly, yes. Domain registrants are required to provide accurate information. However, some registrars do offer privacy services that replace the registrant’s contact information with their own.

3. Can I hide my information if I register a domain?

Yes, many registrars offer privacy protection services (for an additional fee) that can hide your information in a WHOIS search.

4. Is accessing WHOIS information legal?

Yes, accessing WHOIS information is legal. The data is publicly available and intended to maintain transparency on the internet.

5. Can I use WHOIS data for marketing?

While the data is publicly available, using it for unsolicited marketing or spam is against the terms of most domain registries and can lead to penalties.

"Amateurs hack systems, professionals hack people."
-- Bruce Schneier, a renown computer security professional
Scroll to Top