1.What is the transmission rate of Ethernet LANs? What are some of the physical

Question

1.What is the transmission rate of Ethernet LANs? What are some of the physical media that Ethernet can run over?

2. Why will two ISPs at the same level of the hierarchy often peer with each other? How does an IXP earn money?

3. Suppose Host A wants to send a large file to Host B. The path from Host A to Host B has three links, of rates ??1 = 500 kbps, ??2= 2 Mbps, and ??3= 1 Mbps.

a. Assuming no other traffic in the network, what is the throughput for the file transfer?

b. Suppose the file is 4 million bytes. Dividing the file size by the throughput, roughly how long will it take to transfer the file to Host B?

4. a.) 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 ?????? of ??????1, . . . , ????????. Further suppose that the Web page associated with the link contains exactly one object, consisting of a small amount of HTML text. Let ??????0 denote the ?????? 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?

b. Referring to Problem 4)a) suppose the HTML file references eight very small objects on the same server. Neglecting transmission times, how much time elapses with

i. [1 point] Non- persistent HTTP with no parallel TCP connections?

ii. [1 point] Non- persistent HTTP with the browser configured for 5 parallel connections?

iii. [1 point] Persistent HTTP?

5. Write down the differences between POP3 and IMAP protocols

Explanation / Answer

1. Ethernet LANs have transmission rates of 10 Mbps, 100 Mbps, 1 Gbps and 10 Gbps For an X Mbps Ethernet (where X = 10, 100, 1,000 or 10,000), a user can continuously transmit at the rate X Mbps if that user is the only person sending data. If there are more than one active user, then each user cannot continuously transmit at X Mbps.

2.Most people know certain things about the Internet. They know that cables run under the sea, that wires come into your homes, and that modems carry the digital signals to your devices.

But they

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