pinvoke.net: Edit: dnsapi.dnsquery

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Summary: A generic query interface to the DNS namespace, implemented in multiple forms to facilitate different character encoding.

!!!!C# Signature:
        /// <summary>
        /// Provides a DNS query resolution interface
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682016(v=vs.85).aspx
        /// </summary>
        /// <param name="lpstrName">A pointer to a string that represents the DNS name to query</param>
        /// <param name="wType">A value that represents the Resource Record DNS Record Type that is queried</param>
        /// <param name="Options">A value that contains a bitmap of the DNS Query Options to use in the DNS query</param>
        /// <param name="pExtra">Reserved for future use and must be set to NULL</param>
        /// <param name="ppQueryResultsSet">A pointer to a pointer that points to the list of RRs that comprise the response</param>
        /// <param name="pReserved">Reserved for future use and must be set to NULL</param>
        /// <returns>Success (0), or the DNS-specific error defined in Winerror.h</returns>
        [DllImport("dnsapi", EntryPoint = "DnsQuery_W", CharSet = CharSet.Unicode, SetLastError = true, ExactSpelling = true)]
        public static extern int DnsQuery([MarshalAs(UnmanagedType.VBByRefStr)] ref string lpstrName, DnsRecordTypes wType, DnsQueryOptions Options, IntPtr pExtra, ref IntPtr ppQueryResultsSet, IntPtr pReserved);

/// <summary>
        /// Frees memory allocated for DNS records obtained by using the DnsQuery function
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682021(v=vs.85).aspx
        /// </summary>
        /// <param name="pRecordList">A pointer to the DNS_RECORD structure that contains the list of DNS records to be freed</param>
        /// <param name="FreeType">A specifier of how the record list should be freed</param>
        [DllImport("dnsapi", CharSet = CharSet.Auto, SetLastError = true)]
        public static extern void DnsRecordListFree(IntPtr pRecordList, DNS_FREE_TYPE FreeType);

!!!!User-Defined Types:
C#
	/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982162(v=vs.85).aspx
        /// </summary>
        [Flags]
        public enum DnsQueryOptions
        {
            DNS_QUERY_STANDARD = 0x0,
            DNS_QUERY_ACCEPT_TRUNCATED_RESPONSE = 0x1,
            DNS_QUERY_USE_TCP_ONLY = 0x2,
            DNS_QUERY_NO_RECURSION = 0x4,
            DNS_QUERY_BYPASS_CACHE = 0x8,
            DNS_QUERY_NO_WIRE_QUERY = 0x10,
            DNS_QUERY_NO_LOCAL_NAME = 0x20,
            DNS_QUERY_NO_HOSTS_FILE = 0x40,
            DNS_QUERY_NO_NETBT = 0x80,
            DNS_QUERY_WIRE_ONLY = 0x100,
            DNS_QUERY_RETURN_MESSAGE = 0x200,
            DNS_QUERY_MULTICAST_ONLY = 0x400,
            DNS_QUERY_NO_MULTICAST = 0x800,
            DNS_QUERY_TREAT_AS_FQDN = 0x1000,
            DNS_QUERY_ADDRCONFIG = 0x2000,
            DNS_QUERY_DUAL_ADDR = 0x4000,
            DNS_QUERY_MULTICAST_WAIT = 0x20000,
            DNS_QUERY_MULTICAST_VERIFY = 0x40000,
            DNS_QUERY_DONT_RESET_TTL_VALUES = 0x100000,
            DNS_QUERY_DISABLE_IDN_ENCODING = 0x200000,
            DNS_QUERY_APPEND_MULTILABEL = 0x800000,
            DNS_QUERY_RESERVED = unchecked((int)0xF0000000)
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982162(v=vs.85).aspx
        /// Also see http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml
        /// </summary>
        public enum DnsRecordTypes
        {
            DNS_TYPE_A = 0x1,
            DNS_TYPE_NS = 0x2,
            DNS_TYPE_MD = 0x3,
            DNS_TYPE_MF = 0x4,
            DNS_TYPE_CNAME = 0x5,
            DNS_TYPE_SOA = 0x6,
            DNS_TYPE_MB = 0x7,
            DNS_TYPE_MG = 0x8,
            DNS_TYPE_MR = 0x9,
            DNS_TYPE_NULL = 0xA,
            DNS_TYPE_WKS = 0xB,
            DNS_TYPE_PTR = 0xC,
            DNS_TYPE_HINFO = 0xD,
            DNS_TYPE_MINFO = 0xE,
            DNS_TYPE_MX = 0xF,
            DNS_TYPE_TEXT = 0x10,       // This is how it's specified on MSDN
            DNS_TYPE_TXT = DNS_TYPE_TEXT,
            DNS_TYPE_RP = 0x11,
            DNS_TYPE_AFSDB = 0x12,
            DNS_TYPE_X25 = 0x13,
            DNS_TYPE_ISDN = 0x14,
            DNS_TYPE_RT = 0x15,
            DNS_TYPE_NSAP = 0x16,
            DNS_TYPE_NSAPPTR = 0x17,
            DNS_TYPE_SIG = 0x18,
            DNS_TYPE_KEY = 0x19,
            DNS_TYPE_PX = 0x1A,
            DNS_TYPE_GPOS = 0x1B,
            DNS_TYPE_AAAA = 0x1C,
            DNS_TYPE_LOC = 0x1D,
            DNS_TYPE_NXT = 0x1E,
            DNS_TYPE_EID = 0x1F,
            DNS_TYPE_NIMLOC = 0x20,
            DNS_TYPE_SRV = 0x21,
            DNS_TYPE_ATMA = 0x22,
            DNS_TYPE_NAPTR = 0x23,
            DNS_TYPE_KX = 0x24,
            DNS_TYPE_CERT = 0x25,
            DNS_TYPE_A6 = 0x26,
            DNS_TYPE_DNAME = 0x27,
            DNS_TYPE_SINK = 0x28,
            DNS_TYPE_OPT = 0x29,
            DNS_TYPE_DS = 0x2B,
            DNS_TYPE_RRSIG = 0x2E,
            DNS_TYPE_NSEC = 0x2F,
            DNS_TYPE_DNSKEY = 0x30,
            DNS_TYPE_DHCID = 0x31,
            DNS_TYPE_UINFO = 0x64,
            DNS_TYPE_UID = 0x65,
            DNS_TYPE_GID = 0x66,
            DNS_TYPE_UNSPEC = 0x67,
            DNS_TYPE_ADDRS = 0xF8,
            DNS_TYPE_TKEY = 0xF9,
            DNS_TYPE_TSIG = 0xFA,
            DNS_TYPE_IXFR = 0xFB,
            DNS_TYPE_AFXR = 0xFC,
            DNS_TYPE_MAILB = 0xFD,
            DNS_TYPE_MAILA = 0xFE,
            DNS_TYPE_ALL = 0xFF,
            DNS_TYPE_ANY = 0xFF,
            DNS_TYPE_WINS = 0xFF01,
            DNS_TYPE_WINSR = 0xFF02,
            DNS_TYPE_NBSTAT = DNS_TYPE_WINSR
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682056(v=vs.85).aspx
        /// </summary>
        public enum DNS_FREE_TYPE
        {
            DnsFreeFlat = 0,
            DnsFreeRecordList = 1,
            DnsFreeParsedMessageFields = 2
        }

[StructLayout(LayoutKind.Sequential)]
    public struct DNS_RECORD
    {
        public IntPtr pNext;    // DNS_RECORD*
        public IntPtr pName;    // string
        public ushort wType;
        public ushort wDataLength;
        public FlagsUnion Flags;
        public uint dwTtl;
        public uint dwReserved;
        public DataUnion Data;
    }
    /* Below does not work in 64-bit Windows. Above works both in 32-bit and 64-bit Windows.

[StructLayout(LayoutKind.Explicit)]
        public struct DNS_RECORD
        {
            [FieldOffset(0)]
            public IntPtr pNext;        // DNS_RECORD*
            [FieldOffset(4)]
            public IntPtr pName;        // string
            [FieldOffset(8)]
            public ushort wType;
            [FieldOffset(10)]
            public ushort wDataLength;
            [FieldOffset(12)]
            public FlagsUnion Flags;
            [FieldOffset(16)]
            public uint dwTtl;
            [FieldOffset(20)]
            public uint dwReserved;
            [FieldOffset(24)]
            public DataUnion Data;
        }
*/
        [StructLayout(LayoutKind.Explicit)]
        public struct FlagsUnion
        {
            [FieldOffset(0)]
            public uint DW;
            [FieldOffset(0)]
            public DNS_RECORD_FLAGS S;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682084(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_RECORD_FLAGS
        {
            internal uint data;

// DWORD Section :2;
            public uint Section
            {
                get { return data & 0x3u; }
                set { data = (data & ~0x3u) | (value & 0x3u); }
            }

// DWORD Delete :1;
            public uint Delete
            {
                get { return (data >> 2) & 0x1u; }
                set { data = (data & ~(0x1u << 2)) | (value & 0x1u) << 2; }
            }

// DWORD CharSet :2;
            public uint CharSet
            {
                get { return (data >> 3) & 0x3u; }
                set { data = (data & ~(0x3u << 3)) | (value & 0x3u) << 3; }
            }

// DWORD Unused :3;
            public uint Unused
            {
                get { return (data >> 5) & 0x7u; }
                set { data = (data & ~(0x7u << 5)) | (value & 0x7u) << 5; }
            }

// DWORD Reserved :24;
            public uint Reserved
            {
                get { return (data >> 8) & 0xFFFFFFu; }
                set { data = (data & ~(0xFFFFFFu << 8)) | (value & 0xFFFFFFu) << 8; }
            }
        }

[StructLayout(LayoutKind.Explicit)]
        public struct DataUnion
        {
            [FieldOffset(0)]
            public DNS_A_DATA A;
            [FieldOffset(0)]
            public DNS_SOA_DATA SOA, Soa;
            [FieldOffset(0)]
            public DNS_PTR_DATA PTR, Ptr, NS, Ns, CNAME, Cname, DNAME, Dname, MB, Mb, MD, Md, MF, Mf, MG, Mg, MR, Mr;
            [FieldOffset(0)]
            public DNS_MINFO_DATA MINFO, Minfo, RP, Rp;
            [FieldOffset(0)]
            public DNS_MX_DATA MX, Mx, AFSDB, Afsdb, RT, Rt;
            [FieldOffset(0)]
            public DNS_TXT_DATA HINFO, Hinfo, ISDN, Isdn, TXT, Txt, X25;
            [FieldOffset(0)]
            public DNS_NULL_DATA Null;
            [FieldOffset(0)]
            public DNS_WKS_DATA WKS, Wks;
            [FieldOffset(0)]
            public DNS_AAAA_DATA AAAA;
            [FieldOffset(0)]
            public DNS_KEY_DATA KEY, Key;
            [FieldOffset(0)]
            public DNS_SIG_DATA SIG, Sig;
            [FieldOffset(0)]
            public DNS_ATMA_DATA ATMA, Atma;
            [FieldOffset(0)]
            public DNS_NXT_DATA NXT, Nxt;
            [FieldOffset(0)]
            public DNS_SRV_DATA SRV, Srv;
            [FieldOffset(0)]
            public DNS_NAPTR_DATA NAPTR, Naptr;
            [FieldOffset(0)]
            public DNS_OPT_DATA OPT, Opt;
            [FieldOffset(0)]
            public DNS_DS_DATA DS, Ds;
            [FieldOffset(0)]
            public DNS_RRSIG_DATA RRSIG, Rrsig;
            [FieldOffset(0)]
            public DNS_NSEC_DATA NSEC, Nsec;
            [FieldOffset(0)]
            public DNS_DNSKEY_DATA DNSKEY, Dnskey;
            [FieldOffset(0)]
            public DNS_TKEY_DATA TKEY, Tkey;
            [FieldOffset(0)]
            public DNS_TSIG_DATA TSIG, Tsig;
            [FieldOffset(0)]
            public DNS_WINS_DATA WINS, Wins;
            [FieldOffset(0)]
            public DNS_WINSR_DATA WINSR, WinsR, NBSTAT, Nbstat;
            [FieldOffset(0)]
            public DNS_DHCID_DATA DHCID;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682044(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_A_DATA
        {
            public uint IpAddress;          // IP4_ADDRESS IpAddress;
            public System.Net.IPAddress IPAddressObject { get { return new IPAddress((long)IpAddress); } }
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682096(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_SOA_DATA
        {
            public IntPtr pNamePrimaryServer;       // string
            public IntPtr pNameAdministrator;       // string
            public uint dwSerialNo;
            public uint dwRefresh;
            public uint dwRetry;
            public uint dwExpire;
            public uint dwDefaultTtl;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682080(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_PTR_DATA
        {
            public IntPtr pNameHost;        // string
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682067(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_MINFO_DATA
        {
            public IntPtr pNameMailbox;     // string
            public IntPtr pNameErrorsMailbox;       // string
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682070(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_MX_DATA
        {
            public IntPtr pNameExchange;            // string
            public ushort wPreference;
            public ushort Pad;
            public string NameExchange { get { return Marshal.PtrToStringAuto(pNameExchange); } }
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682109(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_TXT_DATA
        {
            public uint dwStringCount;
            public IntPtr pStringArray;     // PWSTR pStringArray[1];

public List<string> Strings
            {
                get
                {
                    List<string> res = new List<string>((int)dwStringCount);
                    for ( int i = 0; i < dwStringCount; ++i )
                    {
                        IntPtr ptr = IntPtr.Add(pStringArray, i);
                        string s = Marshal.PtrToStringUni(ptr);
                        res.Add(s);
                    }

return res;
                }
            }

}

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682074(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_NULL_DATA
        {
            public uint dwByteCount;
            public IntPtr Data;               // BYTE  Data[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682120(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_WKS_DATA
        {
            public uint IpAddress;          // IP4_ADDRESS IpAddress;
            public byte chProtocol;         // UCHAR       chProtocol;
            public IntPtr BitMask;            // BYTE        BitMask[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682035(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_AAAA_DATA
        {
            // IP6_ADDRESS Ip6Address;
            // DWORD IP6Dword[4];
            // This isn't ideal, but it should work without using the fixed and unsafe keywords
            public uint Ip6Address0;
            public uint Ip6Address1;
            public uint Ip6Address2;
            public uint Ip6Address3;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682061(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_KEY_DATA
        {
            public ushort wFlags;
            public byte chProtocol;
            public byte chAlgorithm;
            public IntPtr Key;                // BYTE Key[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682094(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_SIG_DATA
        {
            public IntPtr pNameSigner;      // string
            public ushort wTypeCovered;
            public byte chAlgorithm;
            public byte chLabelCount;
            public uint dwOriginalTtl;
            public uint dwExpiration;
            public uint dwTimeSigned;
            public ushort wKeyTag;
            public ushort Pad;
            public IntPtr Signature;          // BYTE  Signature[1];
        }

public const int DNS_ATMA_MAX_ADDR_LENGTH = 20;
        public const int DNS_ATMA_FORMAT_E164 = 1;
        public const int DNS_ATMA_FORMAT_AESA = 2;

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682041(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_ATMA_DATA
        {
            public byte AddressType;
            // BYTE Address[DNS_ATMA_MAX_ADDR_LENGTH];
            // This isn't ideal, but it should work without using the fixed and unsafe keywords
            public byte Address0;
            public byte Address1;
            public byte Address2;
            public byte Address3;
            public byte Address4;
            public byte Address5;
            public byte Address6;
            public byte Address7;
            public byte Address8;
            public byte Address9;
            public byte Address10;
            public byte Address11;
            public byte Address12;
            public byte Address13;
            public byte Address14;
            public byte Address15;
            public byte Address16;
            public byte Address17;
            public byte Address18;
            public byte Address19;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682076(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_NXT_DATA
        {
            public IntPtr pNameNext;        // string
            public ushort wNumTypes;
            public IntPtr wTypes;           // WORD  wTypes[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682097(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_SRV_DATA
        {
            public IntPtr pNameTarget;      // string
            public ushort uPriority;
            public ushort wWeight;
            public ushort wPort;
            public ushort Pad;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982164(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_NAPTR_DATA
        {
            public ushort wOrder;
            public ushort wPreference;
            public IntPtr pFlags;           // string
            public IntPtr pService;         // string
            public IntPtr pRegularExpression;       // string
            public IntPtr pReplacement;     // string
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392298(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_OPT_DATA
        {
            public ushort wDataLength;
            public ushort wPad;
            public IntPtr Data;               // BYTE Data[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392296(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_DS_DATA
        {
            public ushort wKeyTag;
            public byte chAlgorithm;
            public byte chDigestType;
            public ushort wDigestLength;
            public ushort wPad;
            public IntPtr Digest;             // BYTE Digest[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392301(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_RRSIG_DATA
        {
            public IntPtr pNameSigner;      // string
            public ushort wTypeCovered;
            public byte chAlgorithm;
            public byte chLabelCount;
            public uint dwOriginalTtl;
            public uint dwExpiration;
            public uint dwTimeSigned;
            public ushort wKeyTag;
            public ushort Pad;
            public IntPtr Signature;          // BYTE  Signature[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392297(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_NSEC_DATA
        {
            public IntPtr pNextDomainName;    // string
            public ushort wTypeBitMapsLength;
            public ushort wPad;
            public IntPtr TypeBitMaps;        // BYTE  TypeBitMaps[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392295(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_DNSKEY_DATA
        {
            public ushort wFlags;
            public byte chProtocol;
            public byte chAlgorithm;
            public ushort wKeyLength;
            public ushort wPad;
            public IntPtr Key;                // BYTE Key[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682104(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_TKEY_DATA
        {
            public IntPtr pNameAlgorithm;   // string
            public IntPtr pAlgorithmPacket; // PBYTE (which is BYTE*)
            public IntPtr pKey;             // PBYTE (which is BYTE*)
            public IntPtr pOtherData;       // PBYTE (which is BYTE*)
            public uint dwCreateTime;
            public uint dwExpireTime;
            public ushort wMode;
            public ushort wError;
            public ushort wKeyLength;
            public ushort wOtherLength;
            public byte cAlgNameLength;     // UCHAR cAlgNameLength;
            public int bPacketPointers;     // BOOL  bPacketPointers;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682106(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_TSIG_DATA
        {
            public IntPtr pNameAlgorithm;   // string
            public IntPtr pAlgorithmPacket; // PBYTE (which is BYTE*)
            public IntPtr pSignature;       // PBYTE (which is BYTE*)
            public IntPtr pOtherData;       // PBYTE (which is BYTE*)
            public long i64CreateTime;
            public ushort wFudgeTime;
            public ushort wOriginalXid;
            public ushort wError;
            public ushort wSigLength;
            public ushort wOtherLength;
            public byte cAlgNameLength;     // UCHAR    cAlgNameLength;
            public int bPacketPointers;     // BOOL     bPacketPointers;
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682114(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_WINS_DATA
        {
            public uint dwMappingFlag;
            public uint dwLookupTimeout;
            public uint dwCacheTimeout;
            public uint cWinsServerCount;
            public uint WinsServers;        // IP4_ADDRESS WinsServers[1];
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682113(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_WINSR_DATA
        {
            public uint dwMappingFlag;
            public uint dwLookupTimeout;
            public uint dwCacheTimeout;
            public IntPtr pNameResultDomain;        // string
        }

/// <summary>
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392294(v=vs.85).aspx
        /// </summary>
        [StructLayout(LayoutKind.Sequential)]
        public struct DNS_DHCID_DATA
        {
            public uint dwByteCount;
            public IntPtr DHCID;              // BYTE  DHCID[1];
        }

!!!!Helper Functions:
        /// <summary>
        /// Converts an unsigned int to an ip address object
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982163(v=vs.85).aspx
        /// </summary>
        /// <param name="ipAddress">The unsigned int to convert to an ip address object</param>
        /// <returns>The converted ip address</returns>
        public static IPAddress ConvertUintToIpAddress(uint ipAddress)
        {
            // x86 is in little endian
            // Network byte order (what the IPAddress object requires) is big endian
            // Ex - 0x7F000001 is 127.0.0.1
            var addressBytes = new byte[4];
            addressBytes[0] = (byte)((ipAddress & 0xFF000000u) >> 24);
            addressBytes[1] = (byte)((ipAddress & 0x00FF0000u) >> 16);
            addressBytes[2] = (byte)((ipAddress & 0x0000FF00u) >> 8);
            addressBytes[3] = (byte)(ipAddress & 0x000000FFu);
            return new IPAddress(addressBytes);
        }

/// <summary>
        /// Converts the data from the AAAA record into an ip address object
        /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682140(v=vs.85).aspx
        /// </summary>
        /// <param name="data">The AAAA record to convert</param>
        /// <returns>The converted ip address</returns>
        public static IPAddress ConvertAAAAToIpAddress(DNS_AAAA_DATA data)
        {
            var addressBytes = new byte[16];
            addressBytes[0] = (byte)(data.Ip6Address0 & 0x000000FF);
            addressBytes[1] = (byte)((data.Ip6Address0 & 0x0000FF00) >> 8);
            addressBytes[2] = (byte)((data.Ip6Address0 & 0x00FF0000) >> 16);
            addressBytes[3] = (byte)((data.Ip6Address0 & 0xFF000000) >> 24);
            addressBytes[4] = (byte)(data.Ip6Address1 & 0x000000FF);
            addressBytes[5] = (byte)((data.Ip6Address1 & 0x0000FF00) >> 8);
            addressBytes[6] = (byte)((data.Ip6Address1 & 0x00FF0000) >> 16);
            addressBytes[7] = (byte)((data.Ip6Address1 & 0xFF000000) >> 24);
            addressBytes[8] = (byte)(data.Ip6Address2 & 0x000000FF);
            addressBytes[9] = (byte)((data.Ip6Address2 & 0x0000FF00) >> 8);
            addressBytes[10] = (byte)((data.Ip6Address2 & 0x00FF0000) >> 16);
            addressBytes[11] = (byte)((data.Ip6Address2 & 0xFF000000) >> 24);
            addressBytes[12] = (byte)(data.Ip6Address3 & 0x000000FF);
            addressBytes[13] = (byte)((data.Ip6Address3 & 0x0000FF00) >> 8);
            addressBytes[14] = (byte)((data.Ip6Address3 & 0x00FF0000) >> 16);
            addressBytes[15] = (byte)((data.Ip6Address3 & 0xFF000000) >> 24);

return new IPAddress(addressBytes);
        }

!!!!Alternative Managed API:
Do you know one?  Please contribute it!

!!!!Notes:
See original example provided by Peter A Bromberg, Ph.D.
http://www.eggheadcafe.com/articles/20050129.asp

New example provided by Dylan Jones (jonesdyn@gmail.com).

!!!!Tips & Tricks:
Please add some!

!!!!Sample Code:
C#
    using System;
    using System.Collections.Generic;
    using System.ComponentModel;
    using System.Net;
    using System.Runtime.InteropServices;

namespace DnsTest
    {
        public class Dns
        {
            /// <summary>
            /// Returns a list of exchange server names from the MX records found from the given domain
            /// This function can be easily changed to return data from other DNS records
            /// </summary>
            /// <param name="domain">The domain to query for MX records</param>
            /// <returns>A list of exchange server names from the MX records found from the given domain</returns>
            public static List<string> GetMxRecords(string domain)
            {
                if (Environment.OSVersion.Platform != PlatformID.Win32NT)
                {
                    throw new NotSupportedException();
                }

var recordsArray = IntPtr.Zero;
                try
                {
                    var result = DnsQuery(ref domain, DnsRecordTypes.DNS_TYPE_MX, DnsQueryOptions.DNS_QUERY_BYPASS_CACHE,
                        IntPtr.Zero, ref recordsArray, IntPtr.Zero);
                    if (result != 0)
                    {
                        throw new Win32Exception(result);
                    }

DNS_RECORD record;
                    var recordList = new List<string>();
                    for (var recordPtr = recordsArray; !recordPtr.Equals(IntPtr.Zero); recordPtr = record.pNext)
                    {
                        record = (DNS_RECORD)Marshal.PtrToStructure(recordPtr, typeof(DNS_RECORD));
                        if (record.wType == (int)DnsRecordTypes.DNS_TYPE_MX)
                        {
                            recordList.Add(Marshal.PtrToStringAuto(record.Data.MX.pNameExchange));
                        }
                    }

return recordList;
                }
                finally
                {
                    if (recordsArray != IntPtr.Zero)
                    {
                        DnsRecordListFree(recordsArray, DNS_FREE_TYPE.DnsFreeFlat);
                    }
                }
            }

/// <summary>
            /// Provides a DNS query resolution interface
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682016(v=vs.85).aspx
            /// </summary>
            /// <param name="lpstrName">A pointer to a string that represents the DNS name to query</param>
            /// <param name="wType">A value that represents the Resource Record DNS Record Type that is queried</param>
            /// <param name="Options">A value that contains a bitmap of the DNS Query Options to use in the DNS query</param>
            /// <param name="pExtra">Reserved for future use and must be set to NULL</param>
            /// <param name="ppQueryResultsSet">A pointer to a pointer that points to the list of RRs that comprise the response</param>
            /// <param name="pReserved">Reserved for future use and must be set to NULL</param>
            /// <returns>Success (0), or the DNS-specific error defined in Winerror.h</returns>
            [DllImport("dnsapi", EntryPoint = "DnsQuery_W", CharSet = CharSet.Unicode, SetLastError = true,
                ExactSpelling = true)]
            public static extern int DnsQuery([MarshalAs(UnmanagedType.VBByRefStr)] ref string lpstrName, DnsRecordTypes wType,
                DnsQueryOptions Options, IntPtr pExtra, ref IntPtr ppQueryResultsSet, IntPtr pReserved);

/// <summary>
            /// Frees memory allocated for DNS records obtained by using the DnsQuery function
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682021(v=vs.85).aspx
            /// </summary>
            /// <param name="pRecordList">A pointer to the DNS_RECORD structure that contains the list of DNS records to be freed</param>
            /// <param name="FreeType">A specifier of how the record list should be freed</param>
            [DllImport("dnsapi", CharSet = CharSet.Auto, SetLastError = true)]
            public static extern void DnsRecordListFree(IntPtr pRecordList, DNS_FREE_TYPE FreeType);

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982162(v=vs.85).aspx
            /// </summary>
            [Flags]
            public enum DnsQueryOptions
            {
                DNS_QUERY_STANDARD = 0x0,
                DNS_QUERY_ACCEPT_TRUNCATED_RESPONSE = 0x1,
                DNS_QUERY_USE_TCP_ONLY = 0x2,
                DNS_QUERY_NO_RECURSION = 0x4,
                DNS_QUERY_BYPASS_CACHE = 0x8,
                DNS_QUERY_NO_WIRE_QUERY = 0x10,
                DNS_QUERY_NO_LOCAL_NAME = 0x20,
                DNS_QUERY_NO_HOSTS_FILE = 0x40,
                DNS_QUERY_NO_NETBT = 0x80,
                DNS_QUERY_WIRE_ONLY = 0x100,
                DNS_QUERY_RETURN_MESSAGE = 0x200,
                DNS_QUERY_MULTICAST_ONLY = 0x400,
                DNS_QUERY_NO_MULTICAST = 0x800,
                DNS_QUERY_TREAT_AS_FQDN = 0x1000,
                DNS_QUERY_ADDRCONFIG = 0x2000,
                DNS_QUERY_DUAL_ADDR = 0x4000,
                DNS_QUERY_MULTICAST_WAIT = 0x20000,
                DNS_QUERY_MULTICAST_VERIFY = 0x40000,
                DNS_QUERY_DONT_RESET_TTL_VALUES = 0x100000,
                DNS_QUERY_DISABLE_IDN_ENCODING = 0x200000,
                DNS_QUERY_APPEND_MULTILABEL = 0x800000,
                DNS_QUERY_RESERVED = unchecked((int)0xF0000000)
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982162(v=vs.85).aspx
            /// Also see http://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml
            /// </summary>
            public enum DnsRecordTypes
            {
                DNS_TYPE_A = 0x1,
                DNS_TYPE_NS = 0x2,
                DNS_TYPE_MD = 0x3,
                DNS_TYPE_MF = 0x4,
                DNS_TYPE_CNAME = 0x5,
                DNS_TYPE_SOA = 0x6,
                DNS_TYPE_MB = 0x7,
                DNS_TYPE_MG = 0x8,
                DNS_TYPE_MR = 0x9,
                DNS_TYPE_NULL = 0xA,
                DNS_TYPE_WKS = 0xB,
                DNS_TYPE_PTR = 0xC,
                DNS_TYPE_HINFO = 0xD,
                DNS_TYPE_MINFO = 0xE,
                DNS_TYPE_MX = 0xF,
                DNS_TYPE_TEXT = 0x10,       // This is how it's specified on MSDN
                DNS_TYPE_TXT = DNS_TYPE_TEXT,
                DNS_TYPE_RP = 0x11,
                DNS_TYPE_AFSDB = 0x12,
                DNS_TYPE_X25 = 0x13,
                DNS_TYPE_ISDN = 0x14,
                DNS_TYPE_RT = 0x15,
                DNS_TYPE_NSAP = 0x16,
                DNS_TYPE_NSAPPTR = 0x17,
                DNS_TYPE_SIG = 0x18,
                DNS_TYPE_KEY = 0x19,
                DNS_TYPE_PX = 0x1A,
                DNS_TYPE_GPOS = 0x1B,
                DNS_TYPE_AAAA = 0x1C,
                DNS_TYPE_LOC = 0x1D,
                DNS_TYPE_NXT = 0x1E,
                DNS_TYPE_EID = 0x1F,
                DNS_TYPE_NIMLOC = 0x20,
                DNS_TYPE_SRV = 0x21,
                DNS_TYPE_ATMA = 0x22,
                DNS_TYPE_NAPTR = 0x23,
                DNS_TYPE_KX = 0x24,
                DNS_TYPE_CERT = 0x25,
                DNS_TYPE_A6 = 0x26,
                DNS_TYPE_DNAME = 0x27,
                DNS_TYPE_SINK = 0x28,
                DNS_TYPE_OPT = 0x29,
                DNS_TYPE_DS = 0x2B,
                DNS_TYPE_RRSIG = 0x2E,
                DNS_TYPE_NSEC = 0x2F,
                DNS_TYPE_DNSKEY = 0x30,
                DNS_TYPE_DHCID = 0x31,
                DNS_TYPE_UINFO = 0x64,
                DNS_TYPE_UID = 0x65,
                DNS_TYPE_GID = 0x66,
                DNS_TYPE_UNSPEC = 0x67,
                DNS_TYPE_ADDRS = 0xF8,
                DNS_TYPE_TKEY = 0xF9,
                DNS_TYPE_TSIG = 0xFA,
                DNS_TYPE_IXFR = 0xFB,
                DNS_TYPE_AFXR = 0xFC,
                DNS_TYPE_MAILB = 0xFD,
                DNS_TYPE_MAILA = 0xFE,
                DNS_TYPE_ALL = 0xFF,
                DNS_TYPE_ANY = 0xFF,
                DNS_TYPE_WINS = 0xFF01,
                DNS_TYPE_WINSR = 0xFF02,
                DNS_TYPE_NBSTAT = DNS_TYPE_WINSR
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682056(v=vs.85).aspx
            /// </summary>
            public enum DNS_FREE_TYPE
            {
                DnsFreeFlat = 0,
                DnsFreeRecordList = 1,
                DnsFreeParsedMessageFields = 2
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682082(v=vs.85).aspx
            /// These field offsets could be different depending on endianness and bitness
            /// </summary>
            [StructLayout(LayoutKind.Explicit)]
            public struct DNS_RECORD
            {
                [FieldOffset(0)]
                public IntPtr pNext;        // DNS_RECORD*
                [FieldOffset(4)]
                public IntPtr pName;        // string
                [FieldOffset(8)]
                public ushort wType;
                [FieldOffset(10)]
                public ushort wDataLength;
                [FieldOffset(12)]
                public FlagsUnion Flags;
                [FieldOffset(16)]
                public uint dwTtl;
                [FieldOffset(20)]
                public uint dwReserved;
                [FieldOffset(24)]
                public DataUnion Data;
            }

[StructLayout(LayoutKind.Explicit)]
            public struct FlagsUnion
            {
                [FieldOffset(0)]
                public uint DW;
                [FieldOffset(0)]
                public DNS_RECORD_FLAGS S;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682084(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_RECORD_FLAGS
            {
                internal uint data;

// DWORD Section :2;
                public uint Section
                {
                    get { return data & 0x3u; }
                    set { data = (data & ~0x3u) | (value & 0x3u); }
                }

// DWORD Delete :1;
                public uint Delete
                {
                    get { return (data >> 2) & 0x1u; }
                    set { data = (data & ~(0x1u << 2)) | (value & 0x1u) << 2; }
                }

// DWORD CharSet :2;
                public uint CharSet
                {
                    get { return (data >> 3) & 0x3u; }
                    set { data = (data & ~(0x3u << 3)) | (value & 0x3u) << 3; }
                }

// DWORD Unused :3;
                public uint Unused
                {
                    get { return (data >> 5) & 0x7u; }
                    set { data = (data & ~(0x7u << 5)) | (value & 0x7u) << 5; }
                }

// DWORD Reserved :24;
                public uint Reserved
                {
                    get { return (data >> 8) & 0xFFFFFFu; }
                    set { data = (data & ~(0xFFFFFFu << 8)) | (value & 0xFFFFFFu) << 8; }
                }
            }

[StructLayout(LayoutKind.Explicit)]
            public struct DataUnion
            {
                [FieldOffset(0)]
                public DNS_A_DATA A;
                [FieldOffset(0)]
                public DNS_SOA_DATA SOA, Soa;
                [FieldOffset(0)]
                public DNS_PTR_DATA PTR, Ptr, NS, Ns, CNAME, Cname, DNAME, Dname, MB, Mb, MD, Md, MF, Mf, MG, Mg, MR, Mr;
                [FieldOffset(0)]
                public DNS_MINFO_DATA MINFO, Minfo, RP, Rp;
                [FieldOffset(0)]
                public DNS_MX_DATA MX, Mx, AFSDB, Afsdb, RT, Rt;
                [FieldOffset(0)]
                public DNS_TXT_DATA HINFO, Hinfo, ISDN, Isdn, TXT, Txt, X25;
                [FieldOffset(0)]
                public DNS_NULL_DATA Null;
                [FieldOffset(0)]
                public DNS_WKS_DATA WKS, Wks;
                [FieldOffset(0)]
                public DNS_AAAA_DATA AAAA;
                [FieldOffset(0)]
                public DNS_KEY_DATA KEY, Key;
                [FieldOffset(0)]
                public DNS_SIG_DATA SIG, Sig;
                [FieldOffset(0)]
                public DNS_ATMA_DATA ATMA, Atma;
                [FieldOffset(0)]
                public DNS_NXT_DATA NXT, Nxt;
                [FieldOffset(0)]
                public DNS_SRV_DATA SRV, Srv;
                [FieldOffset(0)]
                public DNS_NAPTR_DATA NAPTR, Naptr;
                [FieldOffset(0)]
                public DNS_OPT_DATA OPT, Opt;
                [FieldOffset(0)]
                public DNS_DS_DATA DS, Ds;
                [FieldOffset(0)]
                public DNS_RRSIG_DATA RRSIG, Rrsig;
                [FieldOffset(0)]
                public DNS_NSEC_DATA NSEC, Nsec;
                [FieldOffset(0)]
                public DNS_DNSKEY_DATA DNSKEY, Dnskey;
                [FieldOffset(0)]
                public DNS_TKEY_DATA TKEY, Tkey;
                [FieldOffset(0)]
                public DNS_TSIG_DATA TSIG, Tsig;
                [FieldOffset(0)]
                public DNS_WINS_DATA WINS, Wins;
                [FieldOffset(0)]
                public DNS_WINSR_DATA WINSR, WinsR, NBSTAT, Nbstat;
                [FieldOffset(0)]
                public DNS_DHCID_DATA DHCID;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682044(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_A_DATA
            {
                public uint IpAddress;          // IP4_ADDRESS IpAddress;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682096(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_SOA_DATA
            {
                public IntPtr pNamePrimaryServer;       // string
                public IntPtr pNameAdministrator;       // string
                public uint dwSerialNo;
                public uint dwRefresh;
                public uint dwRetry;
                public uint dwExpire;
                public uint dwDefaultTtl;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682080(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_PTR_DATA
            {
                public IntPtr pNameHost;        // string
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682067(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_MINFO_DATA
            {
                public IntPtr pNameMailbox;     // string
                public IntPtr pNameErrorsMailbox;       // string
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682070(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_MX_DATA
            {
                public IntPtr pNameExchange;            // string
                public ushort wPreference;
                public ushort Pad;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682109(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_TXT_DATA
            {
                public uint dwStringCount;
                public IntPtr pStringArray;     // PWSTR pStringArray[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682074(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_NULL_DATA
            {
                public uint dwByteCount;
                public IntPtr Data;               // BYTE  Data[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682120(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_WKS_DATA
            {
                public uint IpAddress;          // IP4_ADDRESS IpAddress;
                public byte chProtocol;         // UCHAR       chProtocol;
                public IntPtr BitMask;            // BYTE        BitMask[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682035(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_AAAA_DATA
            {
                // IP6_ADDRESS Ip6Address;
                // DWORD IP6Dword[4];
                // This isn't ideal, but it should work without using the fixed and unsafe keywords
                public uint Ip6Address0;
                public uint Ip6Address1;
                public uint Ip6Address2;
                public uint Ip6Address3;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682061(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_KEY_DATA
            {
                public ushort wFlags;
                public byte chProtocol;
                public byte chAlgorithm;
                public IntPtr Key;                // BYTE Key[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682094(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_SIG_DATA
            {
                public IntPtr pNameSigner;      // string
                public ushort wTypeCovered;
                public byte chAlgorithm;
                public byte chLabelCount;
                public uint dwOriginalTtl;
                public uint dwExpiration;
                public uint dwTimeSigned;
                public ushort wKeyTag;
                public ushort Pad;
                public IntPtr Signature;          // BYTE  Signature[1];
            }

public const int DNS_ATMA_MAX_ADDR_LENGTH = 20;
            public const int DNS_ATMA_FORMAT_E164 = 1;
            public const int DNS_ATMA_FORMAT_AESA = 2;

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682041(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_ATMA_DATA
            {
                public byte AddressType;
                // BYTE Address[DNS_ATMA_MAX_ADDR_LENGTH];
                // This isn't ideal, but it should work without using the fixed and unsafe keywords
                public byte Address0;
                public byte Address1;
                public byte Address2;
                public byte Address3;
                public byte Address4;
                public byte Address5;
                public byte Address6;
                public byte Address7;
                public byte Address8;
                public byte Address9;
                public byte Address10;
                public byte Address11;
                public byte Address12;
                public byte Address13;
                public byte Address14;
                public byte Address15;
                public byte Address16;
                public byte Address17;
                public byte Address18;
                public byte Address19;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682076(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_NXT_DATA
            {
                public IntPtr pNameNext;        // string
                public ushort wNumTypes;
                public IntPtr wTypes;           // WORD  wTypes[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682097(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_SRV_DATA
            {
                public IntPtr pNameTarget;      // string
                public ushort uPriority;
                public ushort wWeight;
                public ushort wPort;
                public ushort Pad;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982164(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_NAPTR_DATA
            {
                public ushort wOrder;
                public ushort wPreference;
                public IntPtr pFlags;           // string
                public IntPtr pService;         // string
                public IntPtr pRegularExpression;       // string
                public IntPtr pReplacement;     // string
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392298(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_OPT_DATA
            {
                public ushort wDataLength;
                public ushort wPad;
                public IntPtr Data;               // BYTE Data[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392296(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_DS_DATA
            {
                public ushort wKeyTag;
                public byte chAlgorithm;
                public byte chDigestType;
                public ushort wDigestLength;
                public ushort wPad;
                public IntPtr Digest;             // BYTE Digest[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392301(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_RRSIG_DATA
            {
                public IntPtr pNameSigner;      // string
                public ushort wTypeCovered;
                public byte chAlgorithm;
                public byte chLabelCount;
                public uint dwOriginalTtl;
                public uint dwExpiration;
                public uint dwTimeSigned;
                public ushort wKeyTag;
                public ushort Pad;
                public IntPtr Signature;          // BYTE  Signature[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392297(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_NSEC_DATA
            {
                public IntPtr pNextDomainName;    // string
                public ushort wTypeBitMapsLength;
                public ushort wPad;
                public IntPtr TypeBitMaps;        // BYTE  TypeBitMaps[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392295(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_DNSKEY_DATA
            {
                public ushort wFlags;
                public byte chProtocol;
                public byte chAlgorithm;
                public ushort wKeyLength;
                public ushort wPad;
                public IntPtr Key;                // BYTE Key[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682104(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_TKEY_DATA
            {
                public IntPtr pNameAlgorithm;   // string
                public IntPtr pAlgorithmPacket; // PBYTE (which is BYTE*)
                public IntPtr pKey;             // PBYTE (which is BYTE*)
                public IntPtr pOtherData;       // PBYTE (which is BYTE*)
                public uint dwCreateTime;
                public uint dwExpireTime;
                public ushort wMode;
                public ushort wError;
                public ushort wKeyLength;
                public ushort wOtherLength;
                public byte cAlgNameLength;     // UCHAR cAlgNameLength;
                public int bPacketPointers;     // BOOL  bPacketPointers;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682106(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_TSIG_DATA
            {
                public IntPtr pNameAlgorithm;   // string
                public IntPtr pAlgorithmPacket; // PBYTE (which is BYTE*)
                public IntPtr pSignature;       // PBYTE (which is BYTE*)
                public IntPtr pOtherData;       // PBYTE (which is BYTE*)
                public long i64CreateTime;
                public ushort wFudgeTime;
                public ushort wOriginalXid;
                public ushort wError;
                public ushort wSigLength;
                public ushort wOtherLength;
                public byte cAlgNameLength;     // UCHAR    cAlgNameLength;
                public int bPacketPointers;     // BOOL     bPacketPointers;
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682114(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_WINS_DATA
            {
                public uint dwMappingFlag;
                public uint dwLookupTimeout;
                public uint dwCacheTimeout;
                public uint cWinsServerCount;
                public uint WinsServers;        // IP4_ADDRESS WinsServers[1];
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682113(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_WINSR_DATA
            {
                public uint dwMappingFlag;
                public uint dwLookupTimeout;
                public uint dwCacheTimeout;
                public IntPtr pNameResultDomain;        // string
            }

/// <summary>
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/dd392294(v=vs.85).aspx
            /// </summary>
            [StructLayout(LayoutKind.Sequential)]
            public struct DNS_DHCID_DATA
            {
                public uint dwByteCount;
                public IntPtr DHCID;              // BYTE  DHCID[1];
            }

/// <summary>
            /// Converts an unsigned int to an ip address object
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/cc982163(v=vs.85).aspx
            /// </summary>
            /// <param name="ipAddress">The unsigned int to convert to an ip address object</param>
            /// <returns>The converted ip address</returns>
            public static IPAddress ConvertUintToIpAddress(uint ipAddress)
            {
                // x86 is in little endian
                // Network byte order (what the IPAddress object requires) is big endian
                // Ex - 0x7F000001 is 127.0.0.1
                var addressBytes = new byte[4];
                addressBytes[0] = (byte)((ipAddress & 0xFF000000u) >> 24);
                addressBytes[1] = (byte)((ipAddress & 0x00FF0000u) >> 16);
                addressBytes[2] = (byte)((ipAddress & 0x0000FF00u) >> 8);
                addressBytes[3] = (byte)(ipAddress & 0x000000FFu);
                return new IPAddress(addressBytes);
            }

/// <summary>
            /// Converts the data from the AAAA record into an ip address object
            /// See http://msdn.microsoft.com/en-us/library/windows/desktop/ms682140(v=vs.85).aspx
            /// </summary>
            /// <param name="data">The AAAA record to convert</param>
            /// <returns>The converted ip address</returns>
            public static IPAddress ConvertAAAAToIpAddress(DNS_AAAA_DATA data)
            {
                var addressBytes = new byte[16];
                addressBytes[0] = (byte)(data.Ip6Address0 & 0x000000FF);
                addressBytes[1] = (byte)((data.Ip6Address0 & 0x0000FF00) >> 8);
                addressBytes[2] = (byte)((data.Ip6Address0 & 0x00FF0000) >> 16);
                addressBytes[3] = (byte)((data.Ip6Address0 & 0xFF000000) >> 24);
                addressBytes[4] = (byte)(data.Ip6Address1 & 0x000000FF);
                addressBytes[5] = (byte)((data.Ip6Address1 & 0x0000FF00) >> 8);
                addressBytes[6] = (byte)((data.Ip6Address1 & 0x00FF0000) >> 16);
                addressBytes[7] = (byte)((data.Ip6Address1 & 0xFF000000) >> 24);
                addressBytes[8] = (byte)(data.Ip6Address2 & 0x000000FF);
                addressBytes[9] = (byte)((data.Ip6Address2 & 0x0000FF00) >> 8);
                addressBytes[10] = (byte)((data.Ip6Address2 & 0x00FF0000) >> 16);
                addressBytes[11] = (byte)((data.Ip6Address2 & 0xFF000000) >> 24);
                addressBytes[12] = (byte)(data.Ip6Address3 & 0x000000FF);
                addressBytes[13] = (byte)((data.Ip6Address3 & 0x0000FF00) >> 8);
                addressBytes[14] = (byte)((data.Ip6Address3 & 0x00FF0000) >> 16);
                addressBytes[15] = (byte)((data.Ip6Address3 & 0xFF000000) >> 24);

return new IPAddress(addressBytes);
            }
        }
    }
Documentation: http://msdn.microsoft.com/en-us/library/windows/desktop/ms682016(v=vs.85).aspx

!!!!Alternative Managed API:
System.Net.Dns.GetHostEntry(Name)