foreach 通过 DNS 主机地址

Question

我有这个代码：

IPHostEntry host = null;
Socket sock;
host = Dns.GetHostEntry("ip..");

foreach (IPAddress address in host.AddressList)
{
    IPEndPoint ipe = new IPEndPoint(address, 7777);
    sock = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
    sock.Connect(ipe);
    if (sock.Connected)
    {
        sock.SendTo(Encoding.UTF8.GetBytes("Hello world"), ipe);
    }
}

此代码在本地主机上运行正常，但是当我写入 vps ip 时，代码无法运行，有什么问题吗？

Answer 1

您的 DNS 设置似乎不正确，Dns.GetHostEntry(string) 在下面的第二点失败。如果 DNS 服务器无法执行反向查找，它不会 return 主机名，因此 Dns.GetHostEntry(string) 不知道要查找什么，并且 return 将是一个空地址列表。

来自 MSDN：https://msdn.microsoft.com/en-us/library/ms143998.aspx

The method tries to parse the address. If the hostNameOrAddress parameter contains a legal IP string literal, then the first phase succeeds.

A reverse lookup using the IP address of the IP string literal is attempted to obtain the host name. This result is set as the HostName property.

The host name from this reverse lookup is used again to obtain all the possible IP addresses associated with the name and set as the AddressList property.

foreach 通过 DNS 主机地址

foreach over DNS host addresses

c#

foreach

host