Dive into the often-misunderstood world of DNS with **“Don’t Break DNS!! // Lesson 2”** from networking expert Chris Greer. While many assume DNS runs exclusively over UDP, this eye-opening episode in the "How DNS Works" series reveals the critical role TCP plays when responses grow too large for UDP packets. Using real-world examples and Wireshark packet captures, Chris demonstrates exactly what happens when a UDP reply gets truncated (the infamous TC flag), forcing the client to retry over a TCP connection. Whether you're troubleshooting mysterious resolution failures or simply want to deepen your understanding of core internet protocols, this lesson delivers clear, practical insights backed by key RFCs like 1123 and 5966.
Don’t let outdated assumptions sabotage your DNS environments—blocking TCP port 53 is a common mistake that can lead to real outages, especially with DNSSEC-enabled zones or ANY queries generating oversized responses. Chris walks through live demos (complete with downloadable .pcap files) showing dig commands triggering the UDP-to-TCP fallback, making the behavior crystal clear and actionable. Perfect for network engineers, security analysts, and anyone pursuing Wireshark certification, this video builds on foundational knowledge and sets the stage for an upcoming deep dive into full recursive lookups. Watch now, sharpen your packet-analysis skills, and make sure you never accidentally “break DNS” again!
