Wireshark | #3 DNS

Introduction: In this video, we dive deep into the Domain Name System (DNS) using practical examples and Wireshark captures. I explain how DNS resolution actually works, moving from the Root level down to Authoritative servers. We will also clarify the confusing difference between Recursive and Iterative DNS queries. We also go through a full lab (Lab 2) covering nslookup commands and analyzing HTTP packets to understand status codes like 200 OK, 304 Not Modified, and 401 Unauthorized. 📝 What I cover in this video: The DNS Hierarchy: Understanding Root, Top-Level Domain (TLD), and Authoritative servers. Recursive vs. Iterative DNS: How your computer finds an IP address by querying servers step-by-step versus asking a server to do the work for you. DNS Records: Explaining A, NS, CNAME, and MX records. Using nslookup: Standard queries to default local DNS servers. Querying specific authoritative servers (e.g., bitsy.mit.edu) directly. Wireshark Analysis: Inspecting HTTP GET requests and responses. Understanding Conditional GET and the 304 Not Modified status. TCP Segment Reassembly for retrieving long documents. Fetching embedded objects (images) in parallel. Handling HTTP Authentication (401 Unauthorized). This tutorial is perfect for: Computer Networking Students. CS students working on Wireshark labs. Anyone preparing for networking exams.