Dns.BeginGetHostEntry Method (IPAddress, AsyncCallback, Object)

// Signals when the resolve has finished. 
public static ManualResetEvent GetHostEntryFinished = 
    new ManualResetEvent(false);

// Define the state object for the callback.  
// Use hostName to correlate calls with the proper result. 
public class ResolveState
{
    string hostName;
    IPHostEntry resolvedIPs;

    public ResolveState(string host)
    {
        hostName = host;
    }

    public IPHostEntry IPs
    {
        get { return resolvedIPs; } 
        set {resolvedIPs = value;}}
    public string host {get {return hostName;} 
        set {hostName = value;}}
}

// Record the IPs in the state object for later use. 
public static void GetHostEntryCallback(IAsyncResult ar)
{
    ResolveState ioContext = (ResolveState)ar.AsyncState;

    ioContext.IPs = Dns.EndGetHostEntry(ar);
    GetHostEntryFinished.Set();
}       

// Determine the Internet Protocol (IP) addresses for  
// this host asynchronously. 
public static void DoGetHostEntryAsync(string hostname)
{
    GetHostEntryFinished.Reset();
    ResolveState ioContext= new ResolveState(hostname);

    Dns.BeginGetHostEntry(ioContext.host, 
        new AsyncCallback(GetHostEntryCallback), ioContext);

    // Wait here until the resolve completes (the callback  
    // calls .Set())
    GetHostEntryFinished.WaitOne();

    Console.WriteLine("EndGetHostEntry({0}) returns:", ioContext.host);

    foreach (IPAddress ip in ioContext.IPs.AddressList)
    {
        Console.WriteLine("    {0}", ip);
    }

}

// Determine the Internet Protocol(IP) addresses for this host.
static void DoResolveToAddresses(String* hostName)
{
    IPAddress * host[] = Dns::ResolveToAddresses(hostName);

    Console::Write("IPs for {0}: ", hostName);
    IEnumerator* ips = host->GetEnumerator();
    while (ips->MoveNext())
    {
        Console::Write("{0} ", ips->Current);
    }
    Console::WriteLine("");        
}