Piggybacking related domain names to improve DNS performance
In this paper, we present a novel approach to exploit the relationships among domain names to improve the cache hit rate for a local DNS server. Using these relationships, an authoritative DNS server (ADNS) can piggyback resolutions for future queries as part of the response message for an initial query. The approach improves the cache hit rate as well as reducing the total queries and responses. The approach is particularly attractive because it can be implemented with no changes to the existing DNS protocol. Trace-based simulations show more than 50% of cache misses can be reduced in the best case while straightforward policies, using frequency and relevancy data for an ADNS, reduce cache misses by 25-40% and DNS traffic by 20-35%. These percentages improve if we focus the policies on resource records with smaller authoritative TTLs. We also show improved performance for hybrid approaches that combine the approach with renewal-based approaches. In conjunction with this work we also did a study on current DNS performance for 20 locations in the United States. The outcome of this study is that the current average DNS latency is generally in the range of 200 300 ms, but range from 500 ms to multiple seconds if we look at the 95% response time. Approaches, such as what we propose, that reduce the amount of DNS traffic will improve the overall response time for applications. (c) 2005 Elsevier B.V. All rights reserved.
dns caching network applications and services