DIAG-02 / DIAGNOSTICS
Subdomain Scanner
Scan a domain for commonly used subdomains like mail, vpn, cpanel, and staging environments.
About the Subdomain Scanner
Subdomains often expose services you've forgotten about — old staging sites, admin panels, or mail interfaces. Enumerating them is a basic step in understanding your domain's footprint. This tool scans a domain for commonly used subdomains.
What this tool checks
It tests a curated list of common subdomain names (mail, vpn, cpanel, dev, staging, and more) against your domain and reports which ones resolve to an IP address.
Why enumerate subdomains
Discovered subdomains reveal your attack surface. Forgotten dev or admin subdomains are a frequent security weak point, and reviewing what's live helps you decommission what shouldn't be.
Frequently asked questions
What is subdomain enumeration?
Subdomain enumeration is the process of discovering the subdomains that exist under a domain. It's used in security assessments to map a domain's full footprint and attack surface.
Is scanning subdomains legal?
Checking DNS resolution for subdomains uses public DNS data and is generally fine for domains you own or are authorized to assess. Always have permission before testing domains you don't control.
Why should I care about old subdomains?
Forgotten subdomains — old staging servers, unused admin panels — often run outdated software and become security liabilities. Finding them lets you secure or remove them.