Dns.Resolve メソッド

DNS ホスト名または IP アドレスを IPHostEntry インスタンスに解決します。

Public Shared Function Resolve( _
   ByVal hostName As String _) As IPHostEntry
[C#]
public static IPHostEntry Resolve(stringhostName);
[C++]
public: static IPHostEntry* Resolve(String* hostName);
[JScript]
public static function Resolve(
   hostName : String) : IPHostEntry;

パラメータ

• hostName
  DNS スタイルのホスト名、または IP アドレス。

戻り値

hostName で指定するホストについてのアドレス情報を格納する IPHostEntry インスタンス。

例外

解説

Resolve メソッドは、DNS サーバーでホスト名または IP アドレスと関連付けられた IP アドレスを照会します。

hostName が複数の IP アドレスと関連付けられた DNS スタイルのホスト名の場合は、そのホスト名に解決された最初の IP アドレスだけが返されます。

使用例

[Visual Basic, C#, C++] Resolve メソッドを使用して、IP アドレスを IPHostEntry インスタンスに解決する例を次に示します。

 
Public Sub DisplayHostAddress(hostString As [String])
    Try
        ' Call the Resolve method passing a DNS style host name or an IP address in 
        ' dotted-quad notation (for example, "www.contoso.com" or "207.46.131.199") to 
        ' obtain an IPHostEntry instance that contains address information for the 
        ' specified host.
        Dim hostInfo As IPHostEntry = Dns.Resolve(hostString)
        ' Get the IP address list that resolves to the host names contained in the Alias 
        ' property.
        Dim address As IPAddress() = hostInfo.AddressList
        ' Get the alias names of the addresses in the IP address list.
        Dim [alias] As [String]() = hostInfo.Aliases
        
        Console.WriteLine(("Host name : " + hostInfo.HostName))
        Console.WriteLine(ControlChars.Cr + "Aliases : ")
        Dim index As Integer
        For index = 0 To [alias].Length - 1
            Console.WriteLine([alias](index))
        Next index
        Console.WriteLine(ControlChars.Cr + "IP Address list :")

        For index = 0 To address.Length - 1
            Console.WriteLine(address(index))
        Next index
    Catch e As SocketException
        Console.WriteLine("SocketException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As ArgumentNullException
        Console.WriteLine("ArgumentNullException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As NullReferenceException
        Console.WriteLine("NullReferenceException caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    Catch e As Exception
        Console.WriteLine("Exception caught!!!")
        Console.WriteLine(("Source : " + e.Source))
        Console.WriteLine(("Message : " + e.Message))
    End Try

[C#] 
try {
    IPHostEntry hostInfo = Dns.Resolve(hostString);
    // Get the IP address list that resolves to the host names contained in the 
    // Alias property.
    IPAddress[] address = hostInfo.AddressList;
    // Get the alias names of the addresses in the IP address list.
    String[] alias = hostInfo.Aliases;

    Console.WriteLine("Host name : " + hostInfo.HostName);
    Console.WriteLine("\nAliases : ");
    for(int index=0; index < alias.Length; index++) {
      Console.WriteLine(alias[index]);
    } 
    Console.WriteLine("\nIP Address list :");
    for(int index=0; index < address.Length; index++) {
       Console.WriteLine(address[index]);
    }
 }
 catch(SocketException e) 
 {
    Console.WriteLine("SocketException caught!!!");
    Console.WriteLine("Source : " + e.Source);
    Console.WriteLine("Message : " + e.Message);
 }
 catch(ArgumentNullException e)
 {
Console.WriteLine("ArgumentNullException caught!!!");
    Console.WriteLine("Source : " + e.Source);
    Console.WriteLine("Message : " + e.Message);
 }
 catch(NullReferenceException e)
 {
     Console.WriteLine("NullReferenceException caught!!!");
     Console.WriteLine("Source : " + e.Source);
     Console.WriteLine("Message : " + e.Message);
 }
 catch(Exception e)
 {
     Console.WriteLine("Exception caught!!!");
     Console.WriteLine("Source : " + e.Source);
     Console.WriteLine("Message : " + e.Message);
 }

[C++] 
try {
   IPHostEntry* hostInfo = Dns::Resolve(hostString);
   // Get the IP address list that resolves to the host names contained in the
   // Alias property.
   IPAddress* address[] = hostInfo->AddressList;
   // Get the alias names of the addresses in the IP address list.
   String*  alias[] = hostInfo->Aliases;

   Console::WriteLine(S"Host name : {0}", hostInfo->HostName);
   Console::WriteLine(S"\nAliases : ");
   for (int index=0; index < alias->Length; index++) {
      Console::WriteLine(alias->Item[index]);
   }
   Console::WriteLine(S"\nIP Address list :");
   for (int index=0; index < address->Length; index++) {
      Console::WriteLine(address->Item[index]);
   }
} catch (SocketException* e) {
   Console::WriteLine(S"SocketException caught!!!");
   Console::WriteLine(S"Source : {0}", e->Source);
   Console::WriteLine(S"Message : {0}", e->Message);
} catch (ArgumentNullException* e) {
   Console::WriteLine(S"ArgumentNullException caught!!!");
   Console::WriteLine(S"Source : {0}", e->Source);
   Console::WriteLine(S"Message : {0}", e->Message);
} catch (NullReferenceException* e) {
   Console::WriteLine(S"NullReferenceException caught!!!");
   Console::WriteLine(S"Source : {0}", e->Source);
   Console::WriteLine(S"Message : {0}", e->Message);
} catch (Exception* e) {
   Console::WriteLine(S"Exception caught!!!");
   Console::WriteLine(S"Source : {0}", e->Source);
   Console::WriteLine(S"Message : {0}", e->Message);
}

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必要条件

プラットフォーム: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 ファミリ, .NET Compact Framework - Windows CE .NET, Common Language Infrastructure (CLI) Standard

.NET Framework セキュリティ:

• DnsPermission (DNS にアクセスするために必要なアクセス許可) PermissionState.Unrestricted (関連する列挙体)

参照

Dns クラス | Dns メンバ | System.Net 名前空間