Break on
$RegExPattern = "^\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}$"
do
  ? "Enter IP Address: "
  gets $input
until RegExpTest($RegExPattern, $input, 1)

? "Valid IP address: " + $input


Function RegExpTest($Pattern, $String, $IgnoreCase)

   Dim $regEx, $Match, $Matches             ; Create variable.

   $regEx = createobject("VBscript.RegExp") ; Create a regular expression.

   $regEx.Pattern    = $Pattern             ; Set pattern.
   $regEx.IgnoreCase = val($IgnoreCase)     ; Set case insensitivity.

   $RegExpTest = $regEx.Test($String)       ; Execute test search.
EndFunction