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Abstract—The Domain Name System (DNS) domain names to be used in network transactions (email, web requests, etc.) instead of IP addresses. The root of the DNS distributed database is managed by 13 root nameservers. We passively measure the performance of one of them: F.root-servers.net. These measurements show an astounding number of bogus queries: from 60-85 % of observed queries were repeated from the same host within the measurement interval. Over 14 % of a root server’s query load is due to queries that violate the DNS specification. Denial of service attacks using root servers are common and occurred throughout our measurement period (7-24 Jan 2001). Though not targeted at the root servers, DOS attacks often use root servers as reflectors toward a victim network. We contrast our observations with those found in an earlier study of DNS root server performance by Danzig et. al. [1]. Keywords—DNS, Root Server I.

This paper reports the design, implementation, and performance of a scalable and efficient tool to replicate Internet information services. Our tool targets replication degrees of tens of thousands of weakly-consistent replicas scattered throughout the Internet's thousands of autonomously administered domains. The main goal of our replication tool is to make existing replication algorithms scale in today's exponentially-growing, autonomouslymanaged internetworks. 1. Introduction Internet services provide large, rapidly evolving, highly accessed, autonomously managed information spaces. To achieve adequate performance, services such as WWW [1] will have to replicate their data in thousands of autonomous networks. As an example of a highly replicated service, take Internet news [5]. Although it manages a dynamic, flat, gigabyte database, it responds to queries in seconds. In contrast, popular WWW and FTP servers are constantly too overloaded to provide reasonable response time to users...

Because of their increasing popularity, Internet information services such as the Web, Internet FTP archives, and Network News, replicate their servers to improve availability, response time, and fault tolerance. Traditional replication algorithms do not address the scale and administrative decentralization of today's internetworks. They manage a single group of replicas and rely on system administrators to hand configure the topologies over which updates travel. While this is appropriate for applications with a small number of replicas that operate within single administrative boundaries, it does not scale in wide-area, highly replicated services whose replicas spread throughout the Internet's thousands of autonomously administered domains. We have proposed and implemented a scalable and efficient tool to replicate widearea, autonomously managed services. We target replication degrees of thousands of weakly consistent replicas. The main goal of our replication tool is to make traditio...

This paper gives an overview about these differences and about currently deployed, developed, and evaluated solutions. Introduction

The immense success of World Wide Web has given rise to some serious problems due to the inability of the existing resources to cope up with the increasing demands. The continuous increase in number of applications that use the web's infrastructure for various purposes has further intensified the problem. The enormous load on web servers and inability of caching mechanisms to keep pace with the heavily increasing demand for web documents have resulted in high latencies, low throughputs and huge amounts of network traffic. As of today, the requirement for a better web is to deliver the information in a speedy, efficient and convenient manner. In order to fulfill these requirements, we propose an approach for replicating the web documents. The approach provides faster access to documents, while reducing the network traffic and web server load. Acknowledgments I am greatly indebted to my thesis supervisor Dr. Deepak Gupta for his constant support and valuable guidance throughout my work...

This document is a brief introduction to the Domain Name System, a distributed directory-assistance database. DNS is in widespread use as a method for translating host names into the corresponding addresses.

The rapid growth of the Internet in users and content has fueled extensive efforts to improve the user's overall Internet experience. A growing number of providers deliver content from multiple servers or proxies to reduce response time by moving content closer to end users. An increasingly popular mechanism to direct clients to the closest point of service is DNS-based redirection, due to its transparency and generality. This paper draws attention to two of the main issues in using DNS: 1) the negative effects of reducing or eliminating the cache lifetimes of DNS information, and 2) the implicit assumption that client nameservers are indicative of actual client location and performance. We quantify the impact of reducing DNS TTL values on web access latency and show that it can increase name resolution latency by two orders of magnitude. Using HTTP and DNS server logs, as well as a large number of dial-up ISP clients, we measure client-nameserver proximity and show that a significant fraction are distant, more than # hops apart. Finally, we suggest protocol modifications to improve the accuracy of DNS-based redirection schemes. I.