/\A   111 
  [.] 255 
  [.] ( \d | [1234]\d | 5[012345] )
  [.] ( \d | [1234]\d | 5[012345] )
\z/x;

##</code><code>##

return 1 if 
  /\A 111 [.] 255 [.] (\d+) [.] (\d+) \z/x
  && $1 <= 55
  && $2 <= 55;