In the course of attending the lecture “Secure Systems” I became aware of a blog post by Geoff Huston on how the Domain Name System (DNS) handles “no such domain name” (NXDOMAIN) responses and which possible attack vectors could result from this. His analysis showed how little effort is necessary to perform a Denial of Service (DoS) attack against random authoritative name servers. After a presentation on this subject I decided to delve a little bit deeper into this topic and I came across the fuss about the new DNS over HTTPS (DoH) protocol earlier this year. The juicy findings during my research inspired me to write an own blog post about it. As with any technology, there are two sides to every coin. It always depends on which perspective you take and what hidden agenda you may pursue. For that reason, this blog post is not intended as a critique of the DoH protocol itself, which can be a valued addition to the internet and appears to have helpful uses. Therefore, my focus was on how DoH might currently be implemented having regard to the overall context. Herein, I will not go into technical details of the DoH protocol and thus refer to the corresponding RFC 8484 containing all these information.Continue reading
Point of Presence (PoP)
How internet giants deliver their data to the world
In the course of attending the lecture “Ultra Large Scale Systems” I was intrigued by the subject of traffic load balancing in ultra-large-scale systems. Out of this large topic I decided to look at traffic distribution at the frontend in detail and held a presentation about it as part of this lecture. As this subject has proven to be difficult to comprehend, as long as all related factors are considered, multiple questions remained open. In order to elaborate on these questions I decided to write this blog post to provide a more detailed view of this topic for those interested. Herein, I will not discuss the subject of traffic load balancing inside an internal infrastructure, however corresponding literature can be found at the end of this article. Despite concentrating only on the frontend part of the equation an in-depth look into the workings of traffic load balancing will be provided.Continue reading
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