error GetHostByName #11001

[Guest_imported]

I'm using a derivated class of CSocket to programm my apliccation. When I introduce the IP adrees there is nothing problem, but if it's the host name, like

http://www.altavista.com,

appears an error message as this, error GetHostByName #11001. Well, #11001 is error code returned by the method WSAGetLastError. My problem is that I don't get to know what's the meanning of this code, and consequently, what am I doing wrong?

COutDlg dlg(this);

CBlockingSocket internet;
CSockAddr saServer;

struct sockaddr_in local;
struct sockaddr_in remot;
PHOSTENT hp;

int s;
unsigned int ip;

s= socket (AF_INET, SOCK_DGRAM,0);
if (s==-1)
{
MessageBox("Error durant la creació del socket",NULL,MB_OK);
exit(1);
}
else
{
MessageBox("Socket Inicialitzat correctament",NULL,MB_OK);
}

UpdateData(TRUE);

dlg.m_name=m_host;
dlg.m_error=21;
dlg.DoModal();

saServer=internet.GetHostByName(m_host);

/* hp=gethostbyname(m_host);

if (hp==NULL)
{
dlg.m_error=WSAGetLastError();
dlg.DoModal();
ip=inet_addr(m_host);
if (ip ==-1)
{
MessageBox("Error en la introducció de l'adreça"
exit(1);
}
}
else memcpy(&ip, hp->h_addr, 4);

/* Estructura de l'adreca del servidor remot */

remot.sin_family = AF_INET;

remot.sin_port = htons(7321);

MessageBox("I'M here"

remot.sin_addr.s_addr = saServer.sin_addr.s_addr;



dlg.m_iphost=ip;
dlg.DoModal();


Thanks for all!