论文标题

在增加DNS响应大小的时代,测量TCP上的DNS:从边缘的视图

Measuring DNS over TCP in the Era of Increasing DNS Response Sizes: A View from the Edge

论文作者

Kosek, Mike, Doan, Trinh Viet, Huber, Simon, Bajpai, Vaibhav

论文摘要

域名系统(DNS)是Internet最关键的部分之一。尽管原始标准定义了DNS对UDP(DOUDP)以及TCP(DOTCP)的DNS的使用,但UDP已成为DNS中使用的主要协议。随着新资源记录(RRS)的引入,DNS响应的大小已大大增加。由于这可能会导致截断或IP碎片,因此根据标准要求的DOTCP后备通过克服DOUDP的尺寸限制来确保成功的DNS响应。但是,直到这个日期,尚未对存根解析器使用DOTCP的效果。我们通过从边缘从DOTCP展示视图来缩小这一差距,从2,500个探针向公共和探测DNS递归解析器发出121m DNS请求。在我们的测量研究中,我们观察到DOTCP通常比Doudp慢,在大多数解析器中,响应时间的相对增加小于37%。虽然可以利用对DOTCP的优化来进一步减少响应时间,但我们表明对公共解析器的支持仍然缺失,因此将来留出​​了优化的空间。此外,我们还发现,公共解析器通常对DOTCP和DOUDP具有可比性的可靠性。但是,探针解析器显示出明显不同的行为:靶向探针解析器的DOTCP查询在4例中的3例中失败,因此不符合标准。这个问题将来只会加剧:随着DNS响应大小将继续增长,对DOTCP的需求将巩固。

The Domain Name System (DNS) is one of the most crucial parts of the Internet. Although the original standard defined the usage of DNS over UDP (DoUDP) as well as DNS over TCP (DoTCP), UDP has become the predominant protocol used in the DNS. With the introduction of new Resource Records (RRs), the sizes of DNS responses have increased considerably. Since this can lead to truncation or IP fragmentation, the fallback to DoTCP as required by the standard ensures successful DNS responses by overcoming the size limitations of DoUDP. However, the effects of the usage of DoTCP by stub resolvers are not extensively studied to this date. We close this gap by presenting a view at DoTCP from the Edge, issuing 12.1M DNS requests from 2,500 probes toward Public as well as Probe DNS recursive resolvers. In our measurement study, we observe that DoTCP is generally slower than DoUDP, where the relative increase in Response Time is less than 37% for most resolvers. While optimizations to DoTCP can be leveraged to further reduce the response times, we show that support on Public resolvers is still missing, hence leaving room for optimizations in the future. Moreover, we also find that Public resolvers generally have comparable reliability for DoTCP and DoUDP. However, Probe resolvers show a significantly different behavior: DoTCP queries targeting Probe resolvers fail in 3 out of 4 cases, and, therefore, do not comply with the standard. This problem will only aggravate in the future: As DNS response sizes will continue to grow, the need for DoTCP will solidify.

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