在win2000下无法创建多播套接字，但在win98、winme下完全正常。

Question

SOCKET m_hSocket;
m_hSocket = WSASocket(AF_INET, SOCK_DGRAM, 0, NULL, 0, 
WSA_FLAG_OVERLAPPED | WSA_FLAG_MULTIPOINT_C_LEAF | WSA_FLAG_MULTIPOINT_D_LEAF);
if (m_hSocket == INVALID_SOCKET){
TRACE("WSASocket:%d\n",WSAGetLastError());
return FALSE;
    }

Answer 1

多播在nt4sp5可能不正常，但2000就完全可以。
here is some code that runs fine on win2000 but fails for the multicast in
nt4sp5
int APIENTRY WinMain(HINSTANCE hInstance,
                     HINSTANCE hPrevInstance,
                     LPSTR     lpCmdLine,
                     int       nCmdShow)
{
 ...
 iRet = WSAStartup (MAKEWORD (2, 2), &wsaData);
 sock = WSASocket (AF_INET, SOCK_DGRAM, NULL, NULL, 0,
WSA_FLAG_MULTIPOINT_C_LEAF | WSA_FLAG_MULTIPOINT_D_LEAF);
 iRet = setsockopt (sock, SOL_SOCKET, SO_REUSEADDR, (char *) &bFlag, sizeof
(BOOL));
...
}