Chapter 9

1. If, in the UDP protocol, there is no guarantee that the packet will arrive at the destination, why are we bothering with it at all?
   Believe it or not, in some contexts, this is an acceptable trade-off. For example, in the VoIP (Voice-over IP) context, dropping one or two packets of the conversation is usually OK, and a price we are glad to pay for improved latency!

2. How can we enable a network cache in Qt? What will get cached there?
   We can use QNetworkAccessManager::setCache() to enable it. This will cache HTTP contents (such as the HTML page, JSON data, and so on) that we get from the network.
3. What is an IP protocol?
   An IP protocol sends data from IP address X to an I/O address Y, and thus has to find a way to reach Y starting from X. A UDP does not do much more than this, but additionally multiplexes data for several ports on X and Y.
4. Is there a Qt cache for DNS...