Part 2: Analyze the Packets using Wireshark.
Part 1: Prepare the Hosts to Capture the Traffic.Instructor Note: Red font color or gray highlights indicate text that appears in the instructor copy only. To accomplish this task, nslookup sends a DNS query to the specified DNS server, receives a DNS reply from that same DNS server, and displays the result.9.2.6 Lab – Using Wireshark to Observe the TCP 3-Way Handshake (Instructor Version) The queried DNS server can be a root DNS server, a top-level-domain DNS server, an authoritative DNS server, or an intermediate DNS server (see the textbook for definitions of these terms). In it is most basic operation, nslookup tool allows the host running the tool to query any specified DNS server for a DNS record. To run it in Windows, open the Command Prompt and run nslookup on the command line. To run nslookup in Linux/Unix, you just type the nslookup command on the command line. nslookup In this lab, we'll make extensive use of the nslookup tool, which is available in most Linux/Unix and Microsoft platforms today. In particular, you may want to review the material on local DNS servers, DNS caching, DNS records and messages, and the TYPE field in the DNS record. Before beginning this lab, you'll probably want to review DNS by reading Section 2.5 of the text. From the DNS client's standpoint, however, the protocol is quite simple – a query is formulated to the local DNS server and a response is received from that server. As shown in Figures 2.21 and 2.22 in the textbook, much can go on " under the covers, " invisible to the DNS clients, as the hierarchical DNS servers communicate with each other to either recursively or iteratively resolve the client's DNS query. Recall that the client's role in the DNS is relatively simple – a client sends a query to its local DNS server, and receives a response back. In this lab, we'll take a closer look at the client side of DNS. As described in Section 2.5 of the textbook, the Domain Name System (DNS) translates hostnames to IP addresses, fulfilling a critical role in the Internet infrastructure.
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