See below for a short function that validates a given IP address:
public static Boolean ValidateIP(string inputIP){var ipParts = inputIP.Split('.');return Int32.Parse(ipParts [0]) < 256 &&Int32.Parse(ipParts [1]) < 256&Int32.Parse(ipParts [2]) < 256 &Int32.Parse(ipParts [3]) < 256;}