title: IP_MULTICAST_TTL and windows7
body: <p>My application is creating an UDP socket and setting some options. One of the option is <code>IP_MULTICAST_TTL.</code></p>
  
  <p>When the application is running on windows 7, and I observe the traffic on the wire with wireshark, I can see that the TTL is always 1, meaning that the <code>setsockopt()</code> is not having any effect (it does not return an error though).</p>
  
  <p>Digging into the code I found that <code>IP_MULTICAST_TTL</code> value is 10 on Windows 7, 3 on other Windows versions.</p>
  
  <p>If I force the value to be 3 on Windows 7, <code>setsockopt()</code> works just fine and wireshark is reporting the right value. </p>
  
  <p>I found this article: <a href="http://support.microsoft.com/kb/257460" rel="nofollow">http://support.microsoft.com/kb/257460</a> and I verify that I'm including Ws2tcpip.h after Winsock2.h and that i am linking against Ws2_32.lib</p>
  
  <p>Any suggestions?</p>