有没有办法从 C# WPF 应用程序刷新 DNS 缓存？ （在 XP、Vista、Win7 上）

Question

有没有办法从 C# WPF 应用程序刷新 DNS 缓存？该应用程序可以在 XP、Vista 或 Windows 7 上运行。

Answer 1

您可以使用 Microsoft 的“dnsapi.dll”中的函数。这将允许您完全以编程方式执行此操作：

using System.Runtime.InteropServices;

[DllImport("dnsapi.dll",EntryPoint="DnsFlushResolverCache")]
private static extern UInt32 DnsFlushResolverCache ();

public static void FlushMyCache() //This can be named whatever name you want and is the function you will call
{
    UInt32 result = DnsFlushResolverCache();
}

我已经对此进行了测试，并且效果很好。

Answer 2

这可能是穷人的解决方案，但您可以使用 System.Diagnostics.Process 启动 ipconfig /flushdns 。

Answer 3

我在互联网上搜索，找不到刷新单个 DNS 条目的方法。致力于故障转移到备份数据中心的工作，这对我来说是需要的。我拆解了 DnsFlushResolverCacheEntry_W 并提出了下面的 p/invoke sig。我将 DnsQuery 方法与 QueryNoWireFlag 和 NoHostFile 标志一起使用。如果有任何结果，我会打电话
DnsFlushResolverCacheEntry_W。对于将来想要做同样事情的人来说，这可能是一个很好的信息

/// <summary>
        /// Removes all related DNS records for the given hostname from the DNS resolver cache.
        /// </summary>
        /// <param name="hostName">The host name to flush from the resolver cache.</param>
        /// <returns>Returns 1 if successful, zero if failed.  No other error information is returned.</returns>
        /// <remarks>
        /// DnsFlushResolverCacheEntry_W is an undocumented method.  From dissembler this method has two possible 
        /// return values 0 or 1.  If the argument is null or the _R_ResolverFlushCacheEntry returns something 
        /// other than zero than the return value is zero.  When _R_ResolverFlushCacheEntry returns zero the 
        /// return value is 1.  Based off this and testing of the method it is assumed that 1 is used to indicate success.  
        /// After calling this method querying the DNS resolver cache returns no results.
        /// 
        /// __stdcall DnsFlushResolverCacheEntry_W(x)
        /// ....
        /// 6DC12729 xor     esi, esi                       // Zero esi
        /// 6DC1272B cmp     [ebp+arg_0], esi               // check if the hostname is null
        /// 6DC1272E jz      loc_6DC1D8B8                   // Jump to end, return value is 0.
        /// 6DC12734 mov     [ebp+ms_exc.registration.TryLevel], esi
        /// 6DC12737 push    esi                            // Push 3 args for method, 2nd is hostname, others null
        /// 6DC12738 push    [ebp+arg_0]
        /// 6DC1273B push    esi
        /// 6DC1273C call    _R_ResolverFlushCacheEntry@12  // call this method 
        /// 6DC12741 mov     [ebp+var_1C], eax              // store return value in local
        /// 6DC12744 mov     [ebp+ms_exc.registration.TryLevel], 0FFFFFFFEh
        /// 6DC1274B
        /// 6DC1274B loc_6DC1274B:                           
        /// 6DC1274B cmp     [ebp+var_1C], esi           
        /// 6DC1274E jnz     loc_6DC1D8E7                   // Error?  jump to block that does etw then return 0
        /// 6DC12754 xor     eax, eax                       // Success?  Set eax to zero
        /// 6DC12756 inc     eax                            // result is 0, increment by 1.  success return value is 1
        /// 6DC12757 call    __SEH_epilog4
        /// 6DC1275C retn    4
        /// 
        /// 6DC1D8B8 xor     eax, eax                       // set return value to zero
        /// 6DC1D8BA jmp     loc_6DC12757                   // jump to end
        /// 
        /// 6DC1D8E7 mov     eax, _WPP_GLOBAL_Control
        /// 6DC1D8EC cmp     eax, offset _WPP_GLOBAL_Control
        /// 6DC1D8F1 jz      short loc_6DC1D8B8
        /// 6DC1D8F3 test    byte ptr [eax+1Ch], 40h
        /// 6DC1D8F7 jz      short loc_6DC1D8B8 // This is probably testing some flag that is used to indicate if ETW is enabled
        /// 6DC1D8F9 push    [ebp+var_1C]
        /// 6DC1D8FC push    offset dword_6DC22494
        /// 6DC1D901 push    0Dh
        /// 6DC1D903 push    dword ptr [eax+14h]
        /// 6DC1D906 push    dword ptr [eax+10h]
        /// 6DC1D909 call    _WPP_SF_q@20    ; WPP_SF_q(x,x,x,x,x)      // This method does some ETW tracing
        /// 6DC1D90E jmp     short loc_6DC1D8B8
        /// </remarks>
        [DllImport("dnsapi.dll", EntryPoint = "DnsFlushResolverCacheEntry_W", CharSet = CharSet.Unicode)]
        public static extern int DnsFlushResolverCacheEntry(string hostName);

Answer 4

试试这个 -

System.Diagnostics.Process process = new System.Diagnostics.Process();
System.Diagnostics.ProcessStartInfo startInfo = new System.Diagnostics.ProcessStartInfo();
startInfo.WindowStyle = System.Diagnostics.ProcessWindowStyle.Hidden;
startInfo.FileName = "cmd.exe";
startInfo.Arguments = "/C ipconfig /flushdns";
process.StartInfo = startInfo;
process.Start();

Answer 5

试试这个：

    static void flushDNS()
    {
        string flushDnsCmd = @"/C ipconfig /flushdns";
        try
        {
            var process = new Process
            {
                StartInfo = new ProcessStartInfo("cmd.exe", flushDnsCmd)

            };
            process.Start();
            
            process.WaitForExit();
            Console.WriteLine(String.Format("Successfully Flushed DNS:'{0}'", flushDnsCmd), EventLogEntryType.Information);

        }
        catch (Exception exp)
        {
            Console.WriteLine(String.Format("Failed to Flush DNS:'{0}' . Error:{1}", flushDnsCmd, exp.Message), EventLogEntryType.Error);
        }
    }