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HW3 - IT 420 Spring 2011 Homework 3 1 Perform the Wireshark...

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IT 420 Spring 2011 Homework 3 1. Perform the Wireshark DNS lab posted on Moodle. Hand in the answers to questions 1 through 23. 1. Run nslookup to obtain the IP address of a Web server in Asia. www.yahoo.co.kr 206.190.60.37 2. Run nslookup to determine the authoritative DNS servers for a university in Europe. nslookup –type=ns ox.ac.uk dns1.ox.ac.uk 3. Run nslookup so that one of the DNS servers obtained in Question 2 is queried for the mail servers for Yahoo! mail. 4. Locate the DNS query and response messages. Are then sent over UDP or TCP? UDP 5. What is the destination port for the DNS query message? What is the source port of DNS response message? Src port: domain (53) Dst port: res-sap (3163) 6. To what IP address is the DNS query message sent? Use ipconfig to determine the IP address of your local DNS server. Are these two IP addresses the same? 128.238.38.160 No, mine is at 192.168.1.2 7. Examine the DNS query message. What “Type” of DNS query is it? Does the query message contain any “answers”? Type : A (Host address) Answer : 0 which means there weren’t any answer. 8. Examine the DNS response message. How many “answers” are provided? What do each of these answers contain? Answer RRs : 2 www.ietf.org : type A, class In, addr 132.151.6.75 www.ieft.org : type A, class In, addr 65.246.255.51 9. Consider the subsequent TCP SYN packet sent by your host. Does the destination IP address of the SYN packet correspond to any of the IP addresses provided in the DNS response message? No 10. This web page contains images. Before retrieving each image, does your host issue new DNS queries? No 11. What is the destination port for the DNS query message? What is the source port of DNS response message? Dst Port: domain (53) Src Port: domain (53) 12. To what IP address is the DNS query message sent? Is this the IP address of your
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