regex101: JavaScript Match Workspace

^start of string

172the literal text 172

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){2}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b|null)

1st Alternative\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){2}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b

\ban ASCII word boundary

Non-Capturing Group(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){2}

{2}repeats the group contents below exactly 2 times:

Non-Capturing Group(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)

1st Alternative25[0-5]

25the literal text 25

Character Class[0-5]

0-5one character from 0 (48₁₀) to 5 (53₁₀)

2nd Alternative2[0-4][0-9]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

0-4one character from 0 (48₁₀) to 4 (52₁₀)

Character Class[0-9]

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

3rd Alternative[01]?[0-9][0-9]?

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-9]

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

Character Class[0-9]?

?matches at most one character from the set below:

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

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Non-Capturing Group(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)

1st Alternative25[0-5]

25the literal text 25

Character Class[0-5]

0-5one character from 0 (48₁₀) to 5 (53₁₀)

2nd Alternative2[0-4][0-9]

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

0-4one character from 0 (48₁₀) to 4 (52₁₀)

Character Class[0-9]

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

3rd Alternative[01]?[0-9][0-9]?

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

Character Class[0-9]

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

Character Class[0-9]?

?matches at most one character from the set below:

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

\ban ASCII word boundary

2nd Alternativenull

nullthe literal text null (case sensitive)

$end of string

26 tokens

Regular Expression

^172\.(?:\b(?:(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){2}(?:25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b|null)$

Unit Tests

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