清单  5.10  通过一个索引获取一个IP地址

1: using System;
2: using System.Net;
3:
4: class ResolveDNS
5: {
6:  IPAddress[] m_arrIPs;
7:
8:  public void Resolve(string strHost)
9:  {
10:  IPHostEntry iphe = Dns.GetHostByName(strHost);
11:  m_arrIPs = iphe.AddressList;
12:  }
13:
14:  public IPAddress this[int nIndex]
15:  {
16:  get
17:  {
18:    return m_arrIPs[nIndex];
19:  }
20:  }
21:
22:  public int Count
23:  {
24:  get { return m_arrIPs.Length; }
25:  }
26: }
27:
28: class DNSResolverApp
29: {
30:  public static void Main()
31:  {
32:  ResolveDNS myDNSResolver = new ResolveDNS();
33:  myDNSResolver.Resolve("http://www.microsoft.com");
34:
35:  int nCount = myDNSResolver.Count;
36:  Console.WriteLine("Found {0} IP's for hostname", nCount);
37:  for (int i=0; i < nCount; i++)
38:    Console.WriteLine(myDNSResolver[i]);
39:  } 
40: }

编译环境：

 Visual Studio .NET2003 version 7.1.3091  Microsoft Visual C# .NET  

 Microsoft .NET Framework version 1.1.4322 sp1

生成的exe文件，执行后报错：

未处理的“System.Net.Sockets.SocketException”类型的异常出现在 system.dll 中。

其他信息: The requested name is valid and was found in the database, but it does not have the correct associated data being resolved for

这是为什么呢？……