What is a Fully Qualified Domain Name (FQDN)?

A Fully Qualified Domain Name (FQDN) is the complete domain name for a specific computer or host on the Internet. It specifies the exact location of a host within the Domain Name System (DNS) hierarchy, consisting of the hostname and the domain name, including the top-level domain. For example, "www.example.com" is an FQDN where "www" is the hostname, "example" is the domain name, and "com" is the top-level domain.

FQDNs are essential for network communication as they provide unambiguous identification of network resources. They allow computers to locate and communicate with specific servers across the Internet without confusion. Unlike partial domain names or hostnames alone, an FQDN includes all levels of the domain hierarchy, making it globally unique and routable.

Tool Description

This FQDN validator checks whether a given string is a properly formatted Fully Qualified Domain Name according to DNS standards. It validates the structure and format of domain names to ensure they follow the rules defined in RFC specifications. The tool accepts domain names with or without subdomains and verifies that each component meets the required criteria for valid domain naming.

The validator checks for proper formatting including allowed characters, label length restrictions, and overall domain structure. It helps identify invalid domain names before they're used in network configurations, DNS records, or web applications.

Features

  • Instant validation - Real-time checking of domain name format
  • Standards compliant - Validates according to DNS and RFC specifications
  • Subdomain support - Accepts domain names with multiple levels (e.g., subdomain.example.com)
  • Clear feedback - Immediate indication of whether the domain name is valid or invalid
  • Simple interface - Easy-to-use input field with validation results
  • Copy functionality - Quickly paste domain names for validation

Use Cases

  • DNS configuration - Verify domain names before adding DNS records
  • Web development - Validate domain names in configuration files and environment variables
  • Domain registration - Check if a desired domain name format is valid before purchasing
  • Network administration - Ensure hostnames and domain names follow proper conventions
  • Data validation - Verify user-submitted domain names in forms and applications
  • API development - Validate domain inputs in APIs and microservices
  • Documentation - Verify domain examples used in technical documentation
  • Troubleshooting - Identify malformed domain names causing connectivity issues