Understanding web co-location is essential for various reasons. For instance, it can help one to assess the collateral damage that denial-of-service attacks or IP-based blocking can cause to the availability of co-located web sites. However, it has been more than a decade since the first study was conducted in 2007. The Internet infrastructure has changed drastically since then, necessitating a renewed study to comprehend the nature of web co-location. In this paper, we conduct an empirical study to revisit web co-location using datasets collected from active DNS measurements. Our results show that the web is still small and centralized to a handful of hosting providers. More specifically, we find that more than 60% of web sites are co-located with at least ten other web sites---a group comprising less popular web sites. In contrast, 17.5% of mostly popular web sites are served from their own servers. Although a high degree of web co-location could make co-hosted sites vulnerable to DoS attacks, our findings show that it is an increasing trend to co-host many web sites and serve them from well-provisioned content delivery networks (CDN) of major providers that provide advanced DoS protection benefits. Regardless of the high degree of web co-location, our analyses of popular block lists indicate that IP-based blocking does not cause severe collateral damage as previously thought.

中文翻译：

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十多年后，网络仍然很小

出于各种原因，了解网络托管至关重要。例如，它可以帮助人们评估拒绝服务攻击或基于 IP 的阻塞可能对共址网站的可用性造成的附带损害。然而，自 2007 年进行第一次研究以来已经过去了十多年。从那时起，互联网基础设施发生了巨大变化，需要重新研究以了解网络托管的性质。在本文中，我们使用从活动 DNS 测量中收集的数据集进行了一项实证研究，以重新审视网络协同定位。我们的结果表明，网络仍然很小并且集中于少数托管服务提供商。更具体地说，我们发现超过 60% 的网站与至少 10 个其他网站位于同一地点——这些网站由不太受欢迎的网站组成。相比之下，17。大多数流行的网站中有 5% 是由它们自己的服务器提供的。尽管高度的网络托管可能会使共同托管的网站容易受到 DoS 攻击，但我们的研究结果表明，共同托管许多网站并通过配置良好的内容交付网络 (CDN) 为它们提供服务是一种日益增长的趋势。提供高级 DoS 保护优势的主要提供商。不管网络托管的程度如何，我们对流行的阻止列表的分析表明，基于 IP 的阻止不会像以前认为的那样造成严重的附带损害。我们的调查结果表明，共同托管许多网站并通过提供高级 DoS 保护优势的主要提供商的配置完善的内容交付网络 (CDN) 为它们提供服务是一种日益增长的趋势。不管网络托管的程度如何，我们对流行的阻止列表的分析表明，基于 IP 的阻止不会像以前认为的那样造成严重的附带损害。我们的调查结果表明，共同托管许多网站并通过提供高级 DoS 保护优势的主要提供商的配置完善的内容交付网络 (CDN) 为它们提供服务是一种日益增长的趋势。不管网络托管的程度如何，我们对流行的阻止列表的分析表明，基于 IP 的阻止不会像以前认为的那样造成严重的附带损害。