What is Subdomain Lookup?

A tool for discovering subdomains associated with any domain. Enter a domain to investigate, and it extracts related subdomains from public DNS information, displaying them with their last-seen dates. Use it for security checks on your own domains, analyzing competitors' service configurations, or streamlining DNS investigations.

What This Tool Can Do

🔒 Security Assessment and Risk Management

Identifying all subdomains under your domain helps you spot forgotten test environments or unintentionally exposed subdomains. These neglected subdomains can become attack targets, making regular checks essential for reducing risks.

🔍 Competitive Analysis and Business Research

Subdomain configurations reveal what services competitors are running. For instance, api.example.com or shop.example.com suggests API services or e-commerce operations, while staging.example.com offers insights into development practices.

📊 Domain Management and Organization

As organizations accumulate subdomains, maintaining an overview becomes challenging. Listing everything in one place makes it easier to identify unused subdomains for deletion or consolidation, helping with infrastructure cleanup.

How to Use

1. Enter a Domain: Type the domain you want to investigate (e.g., example.com) into the input field
2. Start the Search: Click the search button to begin subdomain discovery
3. Review the Results: Discovered subdomains appear in a list with their last-seen dates
4. Load Additional Results: For large result sets, use the "Load More" button to retrieve the next page

Understanding the Results

Search results include the following information:

• Subdomain Name: The FQDN (Fully Qualified Domain Name) of each discovered subdomain
• Last Seen Date: When the subdomain was last observed
• Result Count: The total number of results displayed at the top

Subdomains are sorted by most recent last-seen date, so you can check potentially active ones first.

Practical Applications

💡 Security Audit Usage

Searching your organization's domain uncovers unintentionally exposed subdomains or neglected test environments. Subdomains like dev.example.com or test.example.com often lack the same security controls as production, creating information leak risks if left unmonitored.

📌 Competitive Research and Marketing

Investigating competitors' domains reveals their service landscape. Finding careers.example.com indicates a recruiting site, while blog.example.com suggests active content marketing efforts.

⚙️ Infrastructure Management and Operations

Review all subdomains managed across your organization to identify candidates for cleanup or consolidation. This information also serves as a reference when designing new subdomain naming conventions and maintaining consistency.

Important Considerations

This tool searches based on publicly available DNS information, so private or unlisted subdomains won't appear. Additionally, coverage may not be complete.

When there are many results, the number of items displayed at once may be limited. Use the "Load More" button to retrieve additional subdomains. Keep in mind that the last-seen date indicates when a subdomain was last observed, not a guarantee of current activity.