WHOIS is a protocol for querying databases that store registration information about domain names and IP addresses. Understanding how to read and interpret WHOIS data is essential for cybersecurity professionals, domain investors, legal teams, and anyone researching online entities.
What Information Does WHOIS Contain?
A WHOIS record typically includes:
Registrant Information: The organization or individual who registered the domain, including name, organization, address, phone, and email (though often redacted for privacy).
Administrative Contact: The person authorized to make changes to the domain registration.
Technical Contact: The person responsible for technical issues related to the domain.
Registrar Information: The company through which the domain was registered (like GoDaddy, Namecheap, or Cloudflare).
Important Dates:
- Creation Date: When the domain was first registered
- Updated Date: Last modification to the registration
- Expiration Date: When the registration expires
Nameservers: The DNS servers that resolve the domain to IP addresses.
Reading a WHOIS Record
Here's what a typical WHOIS record looks like:
Domain Name: EXAMPLE.COM
Registry Domain ID: 12345678_DOMAIN_COM-VRSN
Registrar: Example Registrar, Inc.
Creation Date: 1995-08-14T04:00:00Z
Updated Date: 2023-08-14T09:00:00Z
Registry Expiry Date: 2025-08-13T04:00:00Z
Registrar IANA ID: 9999
Domain Status: clientTransferProhibited
Name Server: NS1.EXAMPLE.COM
Name Server: NS2.EXAMPLE.COM
WHOIS for Security Investigations
Security professionals use WHOIS data to:
Investigate phishing domains: New domains (created within the past few days or weeks) hosting login pages are often phishing attempts. The creation date is a key indicator.
Track threat actors: Attackers often register multiple domains. WHOIS data can reveal patterns in registration details, registrars used, or nameserver configurations.
Verify legitimate businesses: Before conducting business with an unfamiliar company, checking their domain age and registration details can reveal red flags.
Identify domain squatters: Finding who registered typosquatting or brand-infringing domains helps with trademark enforcement.
Privacy Protection and GDPR
Since GDPR took effect in 2018, most WHOIS records for domains registered by EU residents show redacted information:
Registrant Name: REDACTED FOR PRIVACY
Registrant Organization: REDACTED FOR PRIVACY
Registrant Email: Please query the RDDS service of the Registrar
Many registrars now offer privacy protection by default, replacing registrant details with proxy information. This is legitimate privacy protection, not necessarily an indicator of malicious intent.
Domain Status Codes
WHOIS records include status codes that indicate the domain's state:
- clientTransferProhibited: Domain cannot be transferred (standard lock)
- serverHold: Domain is not resolving (often due to payment issues)
- pendingDelete: Domain will be deleted soon
- redemptionPeriod: Domain expired and is in grace period
- clientDeleteProhibited: Extra protection against accidental deletion
Multiple status codes often indicate legitimate security measures, not problems.
Using WHOIS Data Responsibly
WHOIS data should be used for:
- Security research and incident response
- Legal investigations and trademark protection
- Due diligence on business partners
- Understanding domain ownership for acquisitions
It should not be used for:
- Spam or unsolicited marketing
- Harassment of domain owners
- Data harvesting for sale
Practical Applications
Domain Purchase Negotiations: Check expiration dates. Domains near expiration might be available for purchase, or the owner might be motivated to sell.
Competitor Research: Understanding when competitors registered key domains and which registrar they use can inform your domain strategy.
Brand Protection: Regular WHOIS monitoring for domains similar to your brand helps catch infringement early.
Look Up WHOIS Data
Use our WHOIS Lookup Tool to query registration information for any domain. The tool provides:
- Full registrant details (when available)
- Registration and expiration dates
- Nameserver information
- Domain status codes
- Registrar details
Understanding WHOIS data empowers you to make informed decisions about domain security, business relationships, and online investigations.