Assume that you have registered a domain name myCoolDomain.com with a registrar. Suppose you outsource your authoritative DNS to the company vDNS. vDNS provides you with two DNS servers: dns1.vdns.com (152.120.1.1) and dns2.vdns.com (152.120.1.2). You host both your web site (www.myCoolDomain.com) and email (@myCoolDomain.com) server in the same host myserver.myCoolDomain.com (100.100.1.1) on your own network. Please answer the following questions:

a. List all DNS records for your domain in (Name, Value, Type) format in TLD .com's DNS servers?

b. List all DNS records for your company's web and email servers in (Name, Value, Type) format in YourDNS's DNS servers for your company?

Problem 2 (10 points) The text below shows the reply sent from the server in response to the HTTP GET message. Answer the following questions, indicating where in the message below you find the answer. The characters are carriage return and line-feed characters. HTTP/1.1 200 OKDate: Tue, 07 Mar 2019 12:39:45ESTServer: Apache/2.0.52 (Fedora) Last-Modified: Sat, 10 Sep 2018 18:27:46 GMTETag: "526c3-f22- a88a4c80"Accept- Ranges: bytesContent-Length: 4500 Keep-Alive: timeout=max=100Connection: Keep-AliveContent-Type: text/html; charset =ISO-8859- 1 CMPSCI 453 / 591 / NTU-ST550A Spring 2005 homepage

a. As the server able to successfully find the document or not? What time was the document reply provided?

b. When was the document last modified?

c. How many bytes are there in the document being returned?

d. What are the first 10 bytes of the document being returned?

e. Did the server agree to a persistent connection?

Problem 3 (8 points) 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 RTT of RTT1, ..., RTTn. Further suppose that the Web page associated with the link contains exactly one object, consisting of a small amount of HTML text. Let RTT0 denote the RTT between the local host and the server containing the object. Assuming zero transmission time of the object,

a. how much time elapses from when the client clicks on the link until the client receives the object?

Now, suppose now, the HTML file references eight very small objects on the same server. Neglecting transmission times, how much additional time elapses for these 10 objects with:

b. Non-persistent HTTP with no parallel TCP connections?

c. Non-persistent HTTP with the browser configured for 5 parallel connections?

d. Persistent HTTP with back-to-back requests in the original single persistent TCP connection?

Problem 4 (4 points) SMTP and Emails

a. What is the difference between MAIL FROM in SMTO and From: in the mail message itself?

b. How does SMTP mark the end of a message body? How about HTTP? Can HTTP use the same method as SMTP to mark the end of a HTTP message body?

Problem 5 (18 points) Consider distributing a file of F = 109 bits to N peers. The server has an upload rate of us, = 20 Mbps, and each peer has a download rate of di =2 Mbps and an upload rate of u. For N = 10, 100, and 1,000 and u = 400 Kbps, 800 Kbps, and 2 Mbps, compute and prepare a chart giving the minimum distribution time for each of the combinations of N and u for both client-server distribution and P2P distribution. You may calculate numbers and create a chart in MS Excel and insert as a table and a chart in MS Word.