msgbox check_ip("1.1.1.1")

Function check_ip(ip)
   Dim regEx
   set regEx = new regExp
   regEx.pattern = "^(([01]?[\d]{1,2})|(2[0-4][\d])|(25[0-5]))(\.(([01]?[\d]{1,2})|(2[0-4][\d])|(25[0-5]))){3}$"
   check_ip = regEx.test(ip)
End Function