Netconf 2020 edition

Netconf 2020 edition

An unconference on the technical, economic and social aspects of network engineering and infrastructure

Pulkit Vaishnav


DNS Lookups in Linux

Submitted Mar 4, 2020

DNS ! Ahh pretty old boring topic for many of us, it indeed is an interesting story beyond the veil. Most of us would know an overview of how DNS works but dwelling in the depths of how DNS, Linux and its tools work together is an interesting journey as well.

Want to send data to anywhere around the world? DNS could be helpful. Think of DNS as a telephone directory having names and numbers. Too simple! I know but wait:)

Every solution comes with a cost, DNS is no different. There are millions of IP addresses and address resolution goes through a set of the process, right from your browser cache → OS cache → Resolver cache → Root Server → TLD server → Name Server.

But how many of you would agree that understanding how DNS resolution works really helps troubleshoot general DNS problems we have? Not enough I would say. So, In this talk, we will discuss how Linux hosts resolve DNS and the components which are involved in the process. Understanding the processes and components not only simplifies troubleshooting DNS issues but also reduces debugging time and effort. We will discuss how a simple looking DNS resolution illustration can get complex within the Linux system.


  • No! We are not discussing “How DNS works?”.
  • DNS lookup in Linux
  • How different tools ping and host works.
  • nsswitch explained
  • DNS in Docker and Kubernetes
  • How can we identify and fix issues


Preliminary knowledge of Linux and few Linux tools like ping, host, strace etc.

Speaker bio

Pulkit Vaishnav is Security Engineer, working towards building a secure and scalable infrastructure at MoEngage. Previously, he has worked with Packetzoom and contributed to scaling, automation and monitoring of the CDN infrastructure which served billions of requests/day on a hybrid cloud infrastructure. He was a co-founder of Hashgrowth an App Store Optimization platform to drive mobile app growth.
Pulkit is a pythonist, open-source enthusiast and likes to explore new technologies. When not working, he likes to travel, explore new cuisines and plays badminton.



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