Dns.Resolve(String) Method

Definition

Namespace:

System.Net

Assembly:

System.Net.NameResolution.dll

Source:

Dns.cs

Caution

Resolve has been deprecated. Use GetHostEntry instead.

Resolves a DNS host name or IP address to an IPHostEntry instance.

public:
 static System::Net::IPHostEntry ^ Resolve(System::String ^ hostName);

[System.Obsolete("Resolve has been deprecated. Use GetHostEntry instead.")]
public static System.Net.IPHostEntry Resolve (string hostName);

[<System.Obsolete("Resolve has been deprecated. Use GetHostEntry instead.")>]
static member Resolve : string -> System.Net.IPHostEntry

Public Shared Function Resolve (hostName As String) As IPHostEntry

Parameters

hostName

String

A DNS-style host name or IP address.

Returns

IPHostEntry

An IPHostEntry instance that contains address information about the host specified in hostName.

Attributes

ObsoleteAttribute

Exceptions

ArgumentNullException

hostName is null.

ArgumentOutOfRangeException

The length of hostName is greater than 255 characters.

SocketException

An error is encountered when resolving hostName.

Examples

The following example uses the Resolve method to resolve an IP address to an IPHostEntry instance.

try
{
   IPHostEntry^ hostInfo = Dns::Resolve( hostString );
   
   // Get the IP address list that resolves to the host names contained in the
   // Alias property.
   array<IPAddress^>^address = hostInfo->AddressList;
   
   // Get the alias names of the addresses in the IP address list.
   array<String^>^alias = hostInfo->Aliases;
   Console::WriteLine( "Host name : {0}", 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 : {0}", e->Source );
   Console::WriteLine( "Message : {0}", e->Message );
}
catch ( ArgumentNullException^ e ) 
{
   Console::WriteLine( "ArgumentNullException caught!!!" );
   Console::WriteLine( "Source : {0}", e->Source );
   Console::WriteLine( "Message : {0}", e->Message );
}
catch ( NullReferenceException^ e ) 
{
   Console::WriteLine( "NullReferenceException caught!!!" );
   Console::WriteLine( "Source : {0}", e->Source );
   Console::WriteLine( "Message : {0}", e->Message );
}
catch ( Exception^ e ) 
{
   Console::WriteLine( "Exception caught!!!" );
   Console::WriteLine( "Source : {0}", e->Source );
   Console::WriteLine( "Message : {0}", e->Message );
}

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);
 }

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

Remarks

The Resolve method queries a DNS server for the IP address associated with a host name or IP address.

When hostName is a DNS-style host name associated with multiple IP addresses, only the first IP address that resolves to that host name is returned.

If the Ipv6Element.Enabled property is set to true, the Aliases property of the IPHostEntry instance returned is not populated by this method and will always be empty.

Note

This member emits trace information when you enable network tracing in your application. For more information, see Network Tracing in the .NET Framework.