Tuesday, November 4, 2008

DNS Performance and Effectiveness of Caching

This paper studies the performance of DNS by taking traces at two campus networks. The result was surprising because I rarely have issues with DNS lookup. Even more surprising is the fact that a large percentage of lookups are never answered.. I suspect the situation has improved since this study was done. Perhaps we need to do another round of study of this sort.

The authors conclude that since short TTL is being employed for a number of applications such as loadbalancing, NS caching is far more effective compared to caching of the actual result. The number of referrals have significant impact on the latency of the lookup.

I like this paper and this sort of large scale studies on the Internet, because there are just so many factors that affect a typical user's Internet experience. Users often do not know where the problem is when they experience a problem. DNS certainly would not be the first place I think of when I have connectivity issues.

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