Distributed systems are only as resilient as we build them to be. Domain Name System (DNS) traffic management is a well-used approach to do so. In this first part of a two-part series, we aim to give a broad overview of DNS and how it’s used for traffic management, as well as the different reasons why we want to use DNS traffic management. If you already have context on what is DNS, what is traffic management, and the reasons why you would need to use DNS traffic management, you can skip directly to where we share our journey and improvements made regarding DNS traffic management at Shopify in Part 2: Shopify’s DNS Traffic Management. A Summarized History of DNS Everything started with humans trying to communicate and a plain text file, even before the advent of the modern internet. The Advanced Research Projects Agency Network (ARPANET) was thought, in 1966, to enable access to remote computers. In 1969, the first computers were connected to ARPANET, followed by the implementation of the Network Control Program (NCP) in 1970. Guided by the need to connect more and more computers together, and as the work on the Transmission Control Protocol (TCP), started in 1974, evolved, TCP/IP was created in the late 1970s to provide the ability to join separate networks in a network of networks and replaced NCP in ARPANET on January 1st, 1983. At the beginning of ARPANET there were just a handful of computers from four different universities connected together, which was easier for people to remember the addresses. This became challenging with new computers joining the network. The Stanford Research Institute provided, through file sharing, a manually maintained file containing the hostnames and related addresses of hosts as provided by member organizations of ARPANET. This file, originally named HOSTS.TXT, is now also broadly known as the /etc/hosts file on Unix and Unix-like systems. A growing network with an increasingly large number of computers meant an increasingly
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