A Precise and Efficient Evaluation of the Proximity Between Web Clients and Their Local DNS Servers

Abstract

Content Distribution Networks (CDNs) attempt to improve Web performance by delivering Web content to end-users from servers located at the edge of the network. An important factor contributing to the performance improvement is the ability of a CDN to select servers in the proximity of the requesting clients. Most CDNs today use the Domain Name System (DNS) to make such server selection decisions. However, DNS provides only the IP address of the client's local DNS server to the CDN, rather than the client's IP address. Therefore, CDNs using DNS-based server selection assume that clients are "close" to their local DNS servers.