P$1(15$ points$).$ Suppose you wanted to do a transaction from a remote client to a server as fast as possible. Would you use UDP or TCP$?$ Why?

P$2(15$ points$).$ Will Web caching reduce the delay for all objects requested by a user or for only some of the objects? Why?

P$3(20$ points$).$ Suppose within your Web browser you click on a link to obtain a Web page. The IP address for the associated URL is not cached in your local host, so a DNS lookup is necessary to obtain the IP address. Suppose that $n$ DNS servers are visited before your host receives the IP address from DNS; the successive visits incur an RTT of RTT $1,$dots,$RT{T}_n.$ Further suppose that the Web page associated with the link contains exactly one object, consisting ofa small amount of HTML text. Let RTT ${?}_0$ denote the RTT between the local host and the server containing the object. Assuming zero transmission time of the object, how much time elapses from when the client clicks on the link until the client receives the object?

P$4(30$ points$).$ Referring to Problem P$3,$ suppose the HTML file references eight very small objects on the same server. Neglecting transmission times, how much time elapses with

a$.$ Non$-$persistent HTTP with no parallel TCP connections?

b$.$ Non$-$persistent HTTP with the browser configured for $6$ parallel connections?

c$.$ Persistent HTTP$?$

P$5(20$ points$).$ Consider a DASH system for which there are $N$ video versions $($at $N$ different rates and qualities$)$ and $N$ audio versions $($at $N$ different rates and qualities$).$ Suppose we want to allow the player to choose at any time any of the $N$ video versions and any of the $N$ audio versions.

a$.$ If we create files so that the audio is mixed in with the video, so server sends only one media stream at given time, how many files will the server need to store $($each a different URL$)?$

b$.$ If the server instead sends the audio and video streams separately and has the client synchronize the streams, how many files will the server need to store?