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 studies 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 reduced
DNS TTL values on web access latency and show that they 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 8 hops apart. Finally, we suggest
protocol modifications to improve the accuracy of DNS-based
redirection schemes.
By: Anees Shaikh, Renu Tewari
Published in: RC21785 in 2000
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