Subdomain Finder - Discover Domain Subdomains
Find and enumerate subdomains for any domain. Discover www, mail, api, ftp, dev, and other common subdomains instantly.
Enter Domain to Find Subdomains
What is a Subdomain Finder?
A subdomain finder is a tool that discovers and enumerates subdomains associated with a given domain name. Subdomains are prefixes added to your root domain (e.g., blog.example.com, shop.example.com) that point to different sections or services of a website. CutUrls.com's Subdomain Finder scans for the most common subdomains by performing DNS resolution checks against Google's public DNS servers, giving you instant results.
Whether you're a security researcher performing reconnaissance, a webmaster auditing your infrastructure, or a developer mapping out a domain's architecture, our tool provides fast, reliable subdomain discovery without requiring any software installation.
How Does Subdomain Discovery Work?
Enter the Domain
Type the root domain you want to scan (e.g., example.com). Our tool strips any protocol or www prefix automatically.
DNS Resolution Scan
The tool queries DNS servers for each common subdomain prefix (www, mail, api, ftp, dev, admin, and more), checking for valid A records.
View Results
All discovered subdomains are displayed with their resolved IP addresses, allowing you to map the domain's infrastructure.
Common Subdomain Uses
📝 Blog (blog.domain.com)
Separate your blog content from the main website. Popular CMS platforms like WordPress are often hosted on a blog subdomain for easier management and content isolation.
🛒 Shop (shop.domain.com)
E-commerce stores frequently use a dedicated subdomain to run platforms like Shopify or WooCommerce independently from the main marketing site.
📧 Mail (mail.domain.com)
Webmail access for email services. Used by hosting providers and organizations to provide browser-based email clients like Roundcube or Horde.
🔧 API (api.domain.com)
REST or GraphQL API endpoints for developers and third-party integrations. Separating APIs on a subdomain enables independent scaling and CORS configuration.
🔐 Admin (admin.domain.com)
Administrative dashboards and control panels. Organizations use admin subdomains to restrict access to management interfaces behind VPNs or IP whitelists.
🧪 Dev / Staging (dev.domain.com)
Development and staging environments used for testing new features before production deployment. Essential for CI/CD workflows and QA teams.
Why Find Subdomains?
🔒 Security Auditing
Discover forgotten or exposed subdomains that could be vulnerable to subdomain takeover attacks. Unmaintained subdomains pointing to decommissioned services are a major security risk.
📊 Competitive Analysis
Map out a competitor's web infrastructure to understand their technology stack, services, and organizational structure. Discover CDN usage, staging environments, and third-party integrations.
🏗️ Infrastructure Mapping
Get a complete picture of your organization's digital footprint. Identify all active services, verify DNS configurations, and ensure nothing is misconfigured or exposed unintentionally.
🔍 SEO & Content Discovery
Subdomains can affect your SEO strategy. Finding all subdomains helps ensure proper canonical tags, avoid duplicate content issues, and consolidate link equity to the main domain.
Subdomain Security Risks
Subdomain Takeover
When a subdomain points to a service (e.g., Heroku, GitHub Pages, S3) that has been removed or unclaimed, attackers can register the service and hijack the subdomain to serve malicious content.
Information Leakage
Development or staging subdomains may expose sensitive debugging information, test credentials, or internal APIs that should not be publicly accessible.
Cookie Scope Issues
Cookies set on the parent domain are accessible by all subdomains. A compromised subdomain could steal session cookies, leading to account takeover across the entire domain.
Phishing via Abandoned Subdomains
Old, forgotten subdomains can be exploited by attackers to create convincing phishing pages that appear to be legitimate parts of a trusted domain.
Subdomains We Check
| Subdomain | Common Purpose | Category |
|---|---|---|
| www | Main website | Web |
| mail / webmail | Email services | |
| smtp / pop | Mail transfer / retrieval | |
| ftp | File transfer | File |
| api | API endpoints | Development |
| admin / cpanel / whm | Administration panels | Management |
| dev / test | Development & testing | Development |
| blog / forum / shop | Content & commerce | Web |
| cdn / static | Content delivery | Performance |
| ns1 / ns2 / ns | Name servers | DNS |
| m / app / portal | Mobile / Applications | Web |
Frequently Asked Questions
What is a subdomain?
A subdomain is a prefix added to your root domain name (e.g., blog.example.com). It functions as a separate section of your website and can point to a different server, application, or service. Subdomains are configured through DNS A or CNAME records.
How does the subdomain finder work?
Our tool performs DNS A record lookups for a list of commonly used subdomain prefixes (www, mail, api, ftp, dev, admin, etc.) against Google's public DNS resolvers. If a valid DNS response is returned with an IP address, the subdomain is confirmed as active.
Is subdomain enumeration legal?
Yes, querying public DNS records is legal. DNS is a public protocol, and the information returned by DNS servers is publicly accessible. However, always ensure you have authorization before performing security testing on domains you don't own.
Why are subdomains important for security?
Subdomains can expose forgotten services, development environments, or admin panels. Subdomain takeover attacks exploit dangling DNS records pointing to decommissioned services. Regular subdomain auditing is a critical part of an organization's security posture.
Can subdomains affect SEO?
Yes. Search engines treat subdomains as separate entities from the root domain. This means link equity isn't automatically shared between a subdomain and the main domain. Many SEO experts recommend using subdirectories (example.com/blog) instead of subdomains (blog.example.com) for better SEO consolidation.
How many subdomains can a domain have?
There is no hard limit on the number of subdomains a domain can have. Technically, DNS allows up to 127 levels of subdomains, and each level can be up to 63 characters long. In practice, most domains use between 5 and 50 subdomains.
What is subdomain takeover?
Subdomain takeover occurs when a subdomain's DNS record points to an external service (like GitHub Pages, Heroku, or AWS S3) that is no longer active. An attacker can claim the service and control what content is served on that subdomain, potentially used for phishing or malware distribution.
What's the difference between a subdomain and a subdirectory?
A subdomain (blog.example.com) is a separate DNS entry that can point to a different server. A subdirectory (example.com/blog) exists on the same server and domain. Subdirectories share domain authority for SEO, while subdomains are treated as separate sites by search engines.
Discover Hidden Subdomains Now
Use CutUrls.com's free Subdomain Finder to map out any domain's infrastructure in seconds. No signup required.