System.Net.Dns.HostResolutionBeginHelper C# (CSharp) Method

        private static IAsyncResult HostResolutionBeginHelper(string hostName, bool justReturnParsedIp, bool includeIPv6, bool throwOnIIPAny, AsyncCallback requestCallback, object state)
        {
            if (hostName == null)
            {
                throw new ArgumentNullException(nameof(hostName));
            }

            if (NetEventSource.IsEnabled) NetEventSource.Info(null, hostName);

            // See if it's an IP Address.
            IPAddress address;
            ResolveAsyncResult asyncResult;
            if (IPAddress.TryParse(hostName, out address))
            {
                if (throwOnIIPAny && (address.Equals(IPAddress.Any) || address.Equals(IPAddress.IPv6Any)))
                {
                    throw new ArgumentException(SR.net_invalid_ip_addr, nameof(hostName));
                }

                asyncResult = new ResolveAsyncResult(address, null, includeIPv6, state, requestCallback);

                if (justReturnParsedIp)
                {
                    IPHostEntry hostEntry = NameResolutionUtilities.GetUnresolvedAnswer(address);
                    asyncResult.StartPostingAsyncOp(false);
                    asyncResult.InvokeCallback(hostEntry);
                    asyncResult.FinishPostingAsyncOp();
                    return asyncResult;
                }
            }
            else
            {
                asyncResult = new ResolveAsyncResult(hostName, null, includeIPv6, state, requestCallback);
            }

            // Set up the context, possibly flow.
            asyncResult.StartPostingAsyncOp(false);

            // Start the resolve.
            Task.Factory.StartNew(
                s => ResolveCallback(s),
                asyncResult,
                CancellationToken.None,
                TaskCreationOptions.DenyChildAttach,
                TaskScheduler.Default);

            // Finish the flowing, maybe it completed?  This does nothing if we didn't initiate the flowing above.
            asyncResult.FinishPostingAsyncOp();
            return asyncResult;
        }