Hostname Validator
Validate hostnames and domain names against RFC standards. Check if a hostname has valid format, length, and characters. Verify fully qualified domain names (FQDNs) for proper DNS configuration.
Hostname Rules (RFC 1123)
- - Total length: 1-253 characters
- - Labels separated by dots
- - Each label: 1-63 characters
- - Labels contain: a-z, A-Z, 0-9, hyphen (-)
- - Labels cannot start or end with hyphen
- - Domain: at least 2 labels, TLD not all numeric
FAQ
What makes a valid hostname?
A valid hostname can contain letters (a-z), numbers (0-9), and hyphens. Each label (part between dots) must be 1-63 characters, cannot start or end with a hyphen, and the total length cannot exceed 253 characters.
What is the difference between a hostname and FQDN?
A hostname is a single label like "server1". A Fully Qualified Domain Name (FQDN) includes the complete domain hierarchy, like "server1.example.com", uniquely identifying a host on the internet.
Can hostnames contain underscores?
Technically, RFC 952 does not allow underscores in hostnames. However, some systems accept them. For maximum compatibility, use only letters, numbers, and hyphens in hostnames.