regex101: Catch domains

Group 1((?:(?!-)[a-zA-Z0-9-]{1,63}(?<!-)\.)+[a-zA-Z]{2,63})

Non-Capturing Group(?:(?!-)[a-zA-Z0-9-]{1,63}(?<!-)\.)+

+repeats the group contents below at least once:

Negative Lookahead(?!-)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Character Class[a-zA-Z0-9-]{1,63}

{1,63}matches between 1 and 63 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

0-9one character from 0 (48₁₀) to 9 (57₁₀)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

Negative Lookbehind(?<!-)

-the literal - (45₁₀ / 55₈ / 2D₁₆)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Character Class[a-zA-Z]{2,63}

{2,63}matches between 2 and 63 characters from the set below:

a-zone character from a (97₁₀) to z (122₁₀) (case sensitive)

A-Zone character from A (65₁₀) to Z (90₁₀) (case sensitive)

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

((?:(?!-)[a-zA-Z0-9-]{1,63}(?<!-)\.)+[a-zA-Z]{2,63})

Test String
New

HostRegexp(`vsdf-dev.example.com`) && PathPrefix(`/ui/`)
HostRegexp(`svwd-dev.example.com`,`cvwf-a-dev.example.com`,`fwsfw-dev.example.com`) && PathPrefix(`/api/`)
Host(`xfwdev.example.com`) && PathPrefix(`/boot-admin/`)
Host(`*`) && PathPrefix(`/api/THAI`)
Host(`dev.example.com`,`dfwdwf.examplexxx.org.jp`) && PathPrefix(`/api/health`,`/api/manage/health`,`/api/manage/features`,`/api/manage/info`)
Host(``) && PathPrefix(`/api/short`)
Host(`\u003cno value\u003e`) && PathPrefix(`/`)

Regular Expressions 101

Regular Expression

Test String
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Regular Expression

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