From: Charles Reis (creis@cs.washington.edu)
Date: Tue Nov 16 2004 - 17:13:20 PST
Development of the Domain Name System
Mockapetris, Dunlap, 1988.
The paper gives a historical look at the transition from the old HOSTS.TXT naming and addressing system to DNS, discussing both the advantages and disadvantages of DNS (in retrospect) as well as the transition itself. It provides a good case study of how difficult it can be to evolve a heavily used system.
Primarily, DNS was designed to be a more scalable solution than HOSTS.TXT, allowing domains to be administered separately in a hierarchical manner, and also to be more flexible and interoperable between different environments. However, there were many concerns about the costs of implementing and moving to a new system as well, requiring both generality (for multiple applications) and simplicity (for multiple compatible implementations).
The authors show how DNS's flexible name hierarchies and caching were important for the successful transition, but that its distributed nature caused significant problems as well, such as the difficulty to measure performance, the diverse incentives and expertise of different administrators, and the difficulty of making upgrades or bug fixes.
Still, it seems that a better comparison with HOSTS.TXT or evaluation of the overall system could have been presented. Although the ability to measure one version of DNS or particular mechanisms might have been obscured by the mixed environment, it seems that the performance of the heterogeneous system (and all its quirks) is exactly what should be compared against the earlier approach. Comparisons of HOSTS.TXT updates and transfer times versus the duration and frequency of DNS queries might have been one performance measure, along with perhaps the total estimated storage requirements for each.
In the end, it is clear that the evolution to DNS was successful and necessary, but also that making such a transition requires significant effort and planning.
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