Webserver with dyn DNS

Ok, thanks.

Now I am trying to use the API described here Integrate with No-IP DDNS - API Information

// NO-IP, Dynamic Update Client, 02.FEB.13

#include <SPI.h>
#include <Ethernet.h>

byte mac[] = { 
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
char server[] = "dynupdate.no-ip.com";

EthernetClient client;

void setup()
{
  Serial.begin(9600);

  Serial.println("[NOIP-DUC]\n");
  Serial.println("Getting IP address from DHCP ...");

  if (Ethernet.begin(mac) == 0)
  {
    Serial.println("Failed to configure Ethernet using DHCP !");
    while (1)
      ;
  }

  Serial.print("My IP address: ");
  Serial.println(Ethernet.localIP());
  Serial.println();

  Serial.print("Connecting to ");
  Serial.print(server);
  Serial.println(" ...");
  client.connect(server, 80);
  
  // checking for answer?
  
  Serial.println("OK. Sending request...\n");
  client.println("GET /nic/update?hostname=mytest.testdomain.com&myip=1.2.3.4 HTTP/1.0");
  client.println("Host: dynupdate.no-ip.com");
  client.println("Authorization: Basic base64-encoded-auth-string");
  client.println("User-Agent: Bobs Update Client WindowsXP/1.2 bob@somedomain.com");
  
  Serial.println("ready?!");
  
}



void loop()
{
  if (client.available())
  {
    char c = client.read();
    Serial.print(c);
  }

  if (Serial.available())
  {
    char c = Serial.read();
    client.print(c);
  }

  if (!client.connected())
  {
    Serial.println();
    Serial.println("Disconnecting.");
    client.stop();
    while (1);
  }
}

Why don't I get any answer? It just disconnects after ~5 seconds.