Validate IPv4 Address C#

validateIpv4Address.cs

/// <summary>
/// Tests string to see if it is valid IPv4 address
/// </summary>
/// <param name="ip">String to test</param>
/// <returns>True if string is IP address, False otherwise</returns>
private bool ValidateIpv4Address(string ip)
{
    IPAddress address;
    return ip != null && ip.Count(c => c == '.') == 3 &&
           IPAddress.TryParse(ip, out address); 
}