IP Parse:

\b(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\b

Assert position at a word boundary «\b»
Match the regular expression below and capture its match into backreference number 1 «(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)»
   Match either the regular expression below (attempting the next alternative only if this one fails) «25[0-5]»
      Match the characters “25” literally «25»
      Match a single character in the range between “0” and “5” «[0-5]»
   Or match regular expression number 2 below (attempting the next alternative only if this one fails) «2[0-4][0-9]»
      Match the character “2” literally «2»
      Match a single character in the range between “0” and “4” «[0-4]»
      Match a single character in the range between “0” and “9” «[0-9]»
   Or match regular expression number 3 below (the entire group fails if this one fails to match) «[01]?[0-9][0-9]?»
      Match a single character present in the list “01” «[01]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
      Match a single character in the range between “0” and “9” «[0-9]»
      Match a single character in the range between “0” and “9” «[0-9]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
Match the character “.” literally «\.»
Match the regular expression below and capture its match into backreference number 2 «(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)»
   Match either the regular expression below (attempting the next alternative only if this one fails) «25[0-5]»
      Match the characters “25” literally «25»
      Match a single character in the range between “0” and “5” «[0-5]»
   Or match regular expression number 2 below (attempting the next alternative only if this one fails) «2[0-4][0-9]»
      Match the character “2” literally «2»
      Match a single character in the range between “0” and “4” «[0-4]»
      Match a single character in the range between “0” and “9” «[0-9]»
   Or match regular expression number 3 below (the entire group fails if this one fails to match) «[01]?[0-9][0-9]?»
      Match a single character present in the list “01” «[01]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
      Match a single character in the range between “0” and “9” «[0-9]»
      Match a single character in the range between “0” and “9” «[0-9]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
Match the character “.” literally «\.»
Match the regular expression below and capture its match into backreference number 3 «(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)»
   Match either the regular expression below (attempting the next alternative only if this one fails) «25[0-5]»
      Match the characters “25” literally «25»
      Match a single character in the range between “0” and “5” «[0-5]»
   Or match regular expression number 2 below (attempting the next alternative only if this one fails) «2[0-4][0-9]»
      Match the character “2” literally «2»
      Match a single character in the range between “0” and “4” «[0-4]»
      Match a single character in the range between “0” and “9” «[0-9]»
   Or match regular expression number 3 below (the entire group fails if this one fails to match) «[01]?[0-9][0-9]?»
      Match a single character present in the list “01” «[01]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
      Match a single character in the range between “0” and “9” «[0-9]»
      Match a single character in the range between “0” and “9” «[0-9]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
Match the character “.” literally «\.»
Match the regular expression below and capture its match into backreference number 4 «(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)»
   Match either the regular expression below (attempting the next alternative only if this one fails) «25[0-5]»
      Match the characters “25” literally «25»
      Match a single character in the range between “0” and “5” «[0-5]»
   Or match regular expression number 2 below (attempting the next alternative only if this one fails) «2[0-4][0-9]»
      Match the character “2” literally «2»
      Match a single character in the range between “0” and “4” «[0-4]»
      Match a single character in the range between “0” and “9” «[0-9]»
   Or match regular expression number 3 below (the entire group fails if this one fails to match) «[01]?[0-9][0-9]?»
      Match a single character present in the list “01” «[01]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
      Match a single character in the range between “0” and “9” «[0-9]»
      Match a single character in the range between “0” and “9” «[0-9]?»
         Between zero and one times, as many times as possible, giving back as needed (greedy) «?»
Assert position at a word boundary «\b»