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 the local DNS cache successfully responds with an with an RTT delay of

$R{T}_0=2$ msecs. Suppose the RTT between the local host and the Web server containing the

object is $R{T}_{HTTP}=80$ msecs.

Suppose that the HTML object references $3$ very small objects on the same server. Neglect

transmission times. How much time $($in msec$)$ elapses from when the client clicks on the link

until the base object and all $3$ additional objects are received from web server at the client,

assuming:

a$)$ non$-$persistent HTTP and no parallel TCP connections

b$)$ the client supports a maximum of $5$ parallel TCP connections, with non$-$persistent HTTP$.$

c$)$ the client supports a maximum of $5$ parallel TCP connections, with persistent HTTP

An institutional network utilizes a $20Mbps$ link to connect to the public internet and reach some

origin web servers.

The time between the moment the router on the internet side of the access link forwards an HTTP

request to the origin servers and the moment it receives a response from them is $1$ seconds

$($internet delay$).$ Assume that HTTP requests are negligibly small. The institutional network adopts

a proxy server that serves requests within the LAN in $1$ msecs, with an average hit rate of $0\mathrm{.}65.$

With the proxy, the average access link delay experienced by requests drops to $20$ msecs.

Calculate the average delay experienced by the requests.