title: Android VpnService class and its builder class
body: <p>I have two questions concerning the <a href="https://developer.android.com/reference/android/net/VpnService.Builder.html" rel="noreferrer">VpnService.Builder</a> class.</p>
  
  <p>Suppose I know an App communicate with its server <code>www.somedomain.com</code>, I know the server's IP address is <code>210.32.204.165</code>.</p>
  
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  <li><p>About the <a href="https://developer.android.com/reference/android/net/VpnService.Builder.html#addAddress(java.lang.String,%20int)" rel="noreferrer">addAddress(String address, int prefixLength)</a> function. In documentation, it says this function "add a network address to the VPN interface", what does that mean? Does it mean the traffic goes to that address (server IP address of an App) will go through VPN or traffic from this address (device IP?) will go through VPN?</p></li>
  <li><p>There is a function <a href="https://developer.android.com/reference/android/net/VpnService.Builder.html#addAllowedApplication(java.lang.String)" rel="noreferrer">addAllowedApplication(String packageName)</a> which specify which app's traffic go through the VPN tunnel. Is there a way or a function to force all traffic send to server <code>www.somedomain.com</code> go through VPN tunnel?</p></li>
  </ol>