There's no "why". There's no justification for the word "improving" either. No interesting content really.<p>Even the man page is better: <a href="http://linux.die.net/man/5/resolv.conf" rel="nofollow">http://linux.die.net/man/5/resolv.conf</a><p>"Optimised" resolv.conf has one line - 127.0.0.1 and the host runs a local cache (dnsmasq / bind / djbdns / ...)
Try out namebench. It hunts down the fastest DNS servers available for your computer to use. namebench runs a fair and thorough benchmark using your web browser history, tcpdump output, or standardized datasets in order to provide an individualized recommendation.<p><a href="http://code.google.com/p/namebench/" rel="nofollow">http://code.google.com/p/namebench/</a>
@viraptor thanks for the feedback. Excluding the "why" was a huge oversight. As far as running a local resolver, it depends on how you architect your infrastructure. Having a single line with 127.0.0.1 introduces a single point of failure. While that might be acceptable for demo/prototyping applications, I think for production deployments you'd want to avoid that. Also running a local resolver adds another service you'll need to monitor and keep up to date.<p>Note: This recommendation is for server setups, where dns latency can easily add ms to processing time. With workstations we can tolerate some latency and should probably benchmark your ISPs resolvers.
I wrote an additional entry on how to find to optimal nameserver:
<a href="http://www.kubieziel.de/blog/archives/1343-Improving-your-resolv.conf-file-part-2.html" rel="nofollow">http://www.kubieziel.de/blog/archives/1343-Improving-your-re...</a>
hmmm.. what distro is this ?<p>Because AFAIK, ubuntu distros (and maybe redhat/fedora even) suffer from multisecond delays due to ipv6 lookups - <a href="https://bugs.launchpad.net/ubuntu/lucid/+source/eglibc/+bug/417757" rel="nofollow">https://bugs.launchpad.net/ubuntu/lucid/+source/eglibc/+bug/...</a><p>I thought this article had some solution to that (other than disabling ipv6, right now) - but dont think so