A. How many tiers exist on the Internet. What are their names?

Make sure to give the correct response for each question: 

1) Consider the structure of the Internet as a network of networks and answer the following questions:

            A. How many tiers exist on the Internet. What are their names?

            B. In which tier do large Content Provider Networks such as Google and Netflix reside?

2) Explain what services does the Application layer use from the Transport Layer. Does the Application layer directly use services provided by the Network Layer? Why/why not?

3) Consider the general operation of DNS. How can DNS be used for censorship? Comment on mechanisms to combat censorship inspired by the work of [Duan+12] "Hold On: Protecting against on-path DNS poisoning".

4) Using Wireshark, capture a DNS request-response exchange on a real network.

Submission: Submit a snapshot of a filtered Wireshark view that shows the request and response alone, and upload the pcap trace you collected.