Consider a chain topology with four hosts $,,$ and $$ as shown below:

ABCD

Host $$ serves as the client and host $$ serves as the server. The four

hosts have the same buffer size.

The link $$ has a rate $=56$ kbps$,$ the link $$ has a rate $=512$ kbps$,$ and the link $$ has a rate $=256$ kbps$.$ Hosts $$ and $$ are separated by $500$ meters, hosts $$ and $$ are separated by $5,000$ meters, and hosts $$ and $$ are separated by $10,000$ meters. The propagation speed along each link is $=3\backslash$times $108$ meters$/$sec$.$ Suppose, host $$ sends a packet of $1,000$ bits to host $.$

i$)$ Ignoring processing and queuing delays, find the end$-$to$-$end delay $2.$

ii$)$ Suppose, network congestion occurs. Which link is likely to become the bottleneck? Explain your answers.

iii$)$ Suppose, the packet that host $$ sent reaches host $.$ Upon receiving the packet, host $$ sends another packet back to host $.$ What is the response time for the packet at host $?$

iv$)$ Suppose, a web cache is installed at client host $$ and the miss rate is $0\mathrm{.}4.$ Find the total response time.