2 Suppose recursive DNS queries are always used. How much time elapses from when the client sends the DNS query until the client receives the IP address, in each of the three DNS queries corresponding to the above three web page requests, respectively?
3 Question 2 (28 marks) HTTP [Learning Outcome 2] (1) Consider the following HTTP GET message sent by a browser, where <cr> and <lf> represent carriage return and line-feed characters. GET /iphone-8/index.html HTTP/1.1<cr><lf>Host: <cr><lf>Connection: close<cr><lf>User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10_6_4; de-de) AppleWebKit/533.16 (KHTML, like Gecko) Version/5.0 Safari/533.16<cr><lf>Accept-Encoding: gzip<cr><lf>Accept-Charset: ISO-8859-1,UTF-8;q=0.7,*;q=0.7<cr><lf>Cache-Control: no-cache<cr><lf>Accept-Language: de,en;q=0.7,en-us;q=0.3<cr><lf>Referer: <cr><lf>Answer the following questions: (a) What is the URL of the document requested by the browser? (b) What version of HTTP is the browser running? (c) Does the browser request a non-persistent or a persistent connection? (d) From which website is the HTTP request triggered? (2) The reply sent from the web server in response to the above HTTP request is shown below