DNS performance and the effectiveness of caching
DNS performance and the effectiveness of caching
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DOI：
10.1145/505202.505223
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发表时间：
2001-11
影响因子：
4.5
通讯作者：
Jaeyeon Jung;Emil Sit;H. Balakrishnan;R. Morris
中科院分区：
文献类型：
--
作者：
Jaeyeon Jung;Emil Sit;H. Balakrishnan;R. Morris
本文提出了一个详细的分析痕迹的DNS和相关的TCP流量收集的互联网链接的麻省理工学院计算机科学实验室和韩国科学技术高级研究院（KAIST）。分析的第一部分详细介绍了这些机构的客户端如何与广域DNS系统交互，重点是性能和故障发生率。第二部分评估DNS缓存的有效性。在最新的MIT跟踪中，23%的查询没有收到任何响应;这些查询占所有跟踪的DNS数据包的一半以上，因为它们被多次重传。大约13%的查找结果表明失败。其中许多故障似乎是由于缺少反向（IP到名称）映射或指向不存在或不适当主机的NS记录造成的。27%的查询发送到根名称servers导致这样的failure.The论文提出了跟踪驱动的模拟，探讨不同的TTL和不同程度的缓存共享DNS缓存命中率的影响。结果表明，将地址（A）记录的TTL减少到几百秒对命中率几乎没有不利影响，并且在超过10或20个客户端之间共享转发DNS缓存几乎没有好处。这些结果表明，DNS的性能并不像人们普遍认为的那样依赖于积极的缓存，并且动态的低TTL A记录绑定的广泛使用不应该降低DNS性能。
This paper presents a detailed analysis of traces of DNS and associated TCP traffic collected on the Internet links of the MIT Laboratory for Computer Science and the Korea Advanced Institute of Science and Technology (KAIST). The first part of the analysis details how clients at these institutions interact with the wide-area DNS system, focusing on performance and prevalence of failures. The second part evaluates the effectiveness of DNS caching.In the most recent MIT trace, 23% of lookups receive no answer; these lookups account for more than half of all traced DNS packets since they are retransmitted multiple times. About 13% of all lookups result in an answer that indicates a failure. Many of these failures appear to be caused by missing inverse (IP-to-name) mappings or NS records that point to non-existent or inappropriate hosts. 27% of the queries sent to the root name servers result in such failures.The paper presents trace-driven simulations that explore the effect of varying TTLs and varying degrees of cache sharing on DNS cache hit rates. The results show that reducing the TTLs of address (A) records to as low as a few hundred seconds has little adverse effect on hit rates, and that little benefit is obtained from sharing a forwarding DNS cache among more than 10 or 20 clients. These results suggest that the performance of DNS is not as dependent on aggressive caching as is commonly believed, and that the widespread use of dynamic, low-TTL A-record bindings should not degrade DNS performance.