What is the regex pattern for domain name?

The regex pattern for domain name is: ^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$.

How does the domain name regex work?

^: Start of string. [a-zA-Z0-9]: Label starts with alphanumeric. (?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?: Optional middle characters (up to 61) ending with alphanumeric. \.)+: Dot separator, repeat for each subdomain. [a-zA-Z]{2,}: TLD (2+ letters). $: End of string.

Regex for Domain Name

Matches valid domain names with proper label formatting. Each label can be up to 63 characters.

Pattern

/^(?:[a-zA-Z0-9](?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?\.)+[a-zA-Z]{2,}$/

Pattern Breakdown

Token	Explanation
^	Start of string
[a-zA-Z0-9]	Label starts with alphanumeric
(?:[a-zA-Z0-9-]{0,61}[a-zA-Z0-9])?	Optional middle characters (up to 61) ending with alphanumeric
\.)+	Dot separator, repeat for each subdomain
[a-zA-Z]{2,}	TLD (2+ letters)
$	End of string

Test Examples

Input	Match?
example.com	Match
sub.domain.co.uk	Match
my-site.org	Match
-invalid.com	No match
no_underscores.com	No match

Common Use Cases

DNS configuration validation
URL parsing
Certificate management

Variations

^[\w.-]+\.[a-zA-Z]{2,}$

Simpler domain match

Other Regex Patterns

Email Address US Phone Number International Phone Number URL IPv4 Address IPv6 Address Date (MM/DD/YYYY)Date (ISO 8601 YYYY-MM-DD)Time (HH:MM, 24-hour)Credit Card Number US Social Security Number US ZIP Code

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