Subdomain Detection Tool

Tool Introduction

The "Subdomain Detection Tool" is a free online tool designed to help users quickly and conveniently discover all subdomains under a specified main domain. By entering the target domain, the tool will utilize various public sources and technologies to scan and list possible subdomains. This is very helpful for website administrators to discover assets, for security engineers to collect target information before penetration testing, or for general users to understand the overall structure of a website.

How to Use

1. In the "Domain" input box, enter the target domain or full URL you need to detect. For example: example.com or https://www.example.com.
2. Click the "Detect" or "Start" button on the tool interface.
3. After the tool finishes execution, the detected subdomain list will be displayed in the text area below, with one subdomain per line.

Input Parameter Description:

• Domain: Required, can be a bare domain (e.g., example.com) or a full URL with a protocol (e.g., https://example.com). It is recommended to enter a bare domain to get more comprehensive subdomain information.

Output Result Format:

• The output result is in plain text format, displayed in a text area. Each discovered subdomain will occupy a separate line.

The Value of Subdomain Detection

Subdomain detection is not just about simply listing parts of a website; it has significant value in several aspects:

• Security Assessment: Discover hidden, unprotected, or expired subdomains, which may become weak points for attackers to infiltrate the main site. It is an important first step in penetration testing and vulnerability discovery, helping to identify potential attack surfaces.
• Asset Management: Helps enterprises fully understand all their online assets, including forgotten or abandoned subdomains, preventing risks brought by "shadow IT" assets.
• Information Gathering: During the reconnaissance phase, subdomains can reveal an organization's network structure, the technology stack used (e.g., dev.example.com might use a development environment), service types (e.g., mail.example.com), and associated business units.
• Compliance Auditing: Ensures that all public-facing subdomains comply with security and privacy policies.

Frequently Asked Questions

• Q: What input formats are supported?
• A: This tool supports bare domains (e.g., example.com) or full URLs with protocols (e.g., https://example.com) as input.
• Q: What is the format of the output?
• A: The output is a plain text list, with each discovered subdomain occupying one line.
• Q: Can all subdomains be detected?
• A: This tool will do its best to discover publicly available subdomains, but due to the limitations of public information sources and detection technologies, it may not be able to discover all internal or highly hidden subdomains.
• Q: Is the detection speed fast?
• A: The detection speed depends on the complexity of the target domain, the current network environment, and the data processing capability of the tool's backend. It usually completes within a few seconds to tens of seconds.

Notes

• Please ensure that the domain you enter is valid and correct; an incorrect domain will not yield effective detection results.
• This tool is for legitimate purposes only, such as personal learning, website security testing, or information gathering. Please do not use this tool for any illegal or unauthorized activities.
• The detection results are for reference only and do not guarantee 100% accuracy and completeness.
• For large or complex domains, there may be many results, please wait patiently and review carefully.