Heijden.DNS.Resolver.GetArpaFromIp C# (CSharp) Method

        public static string GetArpaFromIp(IPAddress ip)
        {
            if (ip.AddressFamily == AddressFamily.InterNetwork)
            {
                StringBuilder sb = new StringBuilder();
                sb.Append("in-addr.arpa.");
                foreach (byte b in ip.GetAddressBytes())
                {
                    sb.Insert(0, string.Format("{0}.", b));
                }
                return sb.ToString();
            }
            if (ip.AddressFamily == AddressFamily.InterNetworkV6)
            {
                StringBuilder sb = new StringBuilder();
                sb.Append("ip6.arpa.");
                foreach (byte b in ip.GetAddressBytes())
                {
                    sb.Insert(0, string.Format("{0:x}.", (b >> 4) & 0xf));
                    sb.Insert(0, string.Format("{0:x}.", (b >> 0) & 0xf));
                }
                return sb.ToString();
            }
            return "?";
        }