Dns.BeginGetHostAddresses Method (String, AsyncCallback, Object)

 

Asynchronously returns the Internet Protocol (IP) addresses for the specified host.

Namespace:   System.Net
Assembly:  System (in System.dll)

<HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading := True)>
Public Shared Function BeginGetHostAddresses (
	hostNameOrAddress As String,
	requestCallback As AsyncCallback,
	state As Object
) As IAsyncResult

Parameters

hostNameOrAddress
Type: System.String

The host name or IP address to resolve.

requestCallback
Type: System.AsyncCallback

An AsyncCallback delegate that references the method to invoke when the operation is complete.

state
Type: System.Object

A user-defined object that contains information about the operation. This object is passed to the requestCallback delegate when the operation is complete.

Return Value

Type: System.IAsyncResult

An IAsyncResult instance that references the asynchronous request.

Exception Condition
ArgumentNullException

hostNameOrAddress is null.

ArgumentOutOfRangeException

The length of hostNameOrAddress is greater than 255 characters.

SocketException

An error is encountered when resolving hostNameOrAddress.

ArgumentException

hostNameOrAddress is an invalid IP address.

The BeginGetHostAddresses method asynchronously queries a DNS server for the IP addresses that are associated with a host name. If hostNameOrAddress is an IP address, this address is returned without querying the DNS server.

System_CAPS_noteNote

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

When an empty string is passed as the host name, this method returns the IPv4 addresses of the local host for all operating systems except Windows Server 2003; for Windows Server 2003, both IPv4 and IPv6 addresses for the local host are returned.

The asynchronous BeginGetHostAddresses operation must be completed by calling the EndGetHostAddresses method. Typically, the method is invoked by the requestCallback delegate.

This method does not block until the operation is complete. To block until the operation is complete, use the GetHostAddresses method.

For more information about using the asynchronous programming model, see Calling Synchronous Methods Asynchronously

DnsPermission

for accessing DNS information. Associated enumeration: PermissionState.Unrestricted

.NET Framework
Available since 2.0
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