Tag Archives: DNS Cache

It’s Always DNS! @ SharkFest’23 EU

Conference Talks, DNS/DNSSEC, , , , , ,

This time (2023) at the yearly Wireshark Developer and User Conference in Europe, I gave a talk about DNS. How could it have been any different –> The title simply had to be ‘It’s Always DNS‘. 😂

“This session dives deeper into the Domain Name System, covering recursive vs. iterative DNS queries, resource records types, TTL & caching, DNS errors, a little DNSSEC, flags, and of course: Wireshark with its useful display filters, custom columns, colouring rules, and so on. And we will explore some other tools to analyze and troubleshoot DNS even further.”

You can watch the whole session and download the slides. And you can do the six challenges at the end of the session as well. (The answers are not in the PDF, but shown in the video.)

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It’s Always DNS – Poster

At a Glance, DNS/DNSSEC, , , , , , ,

We all know the DNS, right? But when we need to troubleshoot it, it’s getting much more complicated than initially thought. DNS ≠ DNS ≠ DNS. And unfortunately: It’s Always DNS.

To get a better understanding of those different kinds of DNS servers (authoritative vs. recursive), DNS messages (recursive, iterative, zone transfer, …) as well as other techniques (conditional forwarding, DoH, …), I draw a poster to have it all at a glance! Here it is:

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DNSSEC KSK Emergency Rollover

DNS/DNSSEC, Security, Tutorial/Howto, , , , , , , , , , , ,

In my last blogpost I showed how to perform a DNSSEC KSK rollover. I did it quite slowly and carefully. This time I am looking into an emergency rollover of the KSK. That is: What to do if your KSK is compromised and you must replace it IMMEDIATELY.

I am listing the procedures and commands I used to replace the KSK of my delegated subdomain dyn.weberdns.de with BIND. And, as you might already suggested, I am showing DNSViz graphs after every step since it greatly reveals the current DNSKEYs etc.

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