What is a bulk subdomain finder?
A bulk subdomain finder maps the publicly reachable hostnames that sit under a domain, such as mail.example.com, api.example.com or blog.example.com, across many domains at once. It enumerates common hostnames and reads the DNS records that resolve them, then reports which ones are live and what they point to. For security researchers, penetration testers and IT administrators, it is a quick way to expand a target's attack surface and to find services that are easy to miss from the outside.
How discovery works
The tool tests a broad dictionary of common hostnames and reads the DNS response for each one. A hostname that returns an address is reported as live; wildcard DNS, where the domain answers for every name, is detected and reported so the results stay meaningful.
Why you should know your subdomains
Forgotten subdomains often run older software, staging environments or exposed admin panels. Discovering them helps you identify what an attacker can see and gives you a checklist to patch, retire or secure each service. A bulk subdomain scanner makes this practical across a whole portfolio, not just a single domain.
A mass subdomain enumeration tool
For authorized security testing, the tool works as a mass subdomain enumeration tool that maps every domain on your list in a single run. The results also serve as a bulk subdomain lookup, grouping hosts so you can review the attack surface quickly.
Frequently asked questions
Can I find subdomains for multiple domains at once?
Yes. Paste up to 25 domains and each one is scanned in the same run, so you get the full host list for your whole portfolio.
Are all subdomains discoverable?
Only those with public DNS records. Internal or unadvertised hostnames that do not resolve publicly cannot be found.
Is subdomain enumeration legal?
Running this against your own domains or assets you are authorized to test is standard practice. Always confirm you have permission before scanning domains you do not control.
Why do I see subdomains I did not create?
Providers, CDNs and email services often add their own hostnames automatically. Each result shows the DNS record, so you can investigate anything unexpected.