Saturday, December 9, 2006

Using OpenDNS with Fedora Core 6

DNS lookups at home were extremely slow for me. For instance, while doing some profiling of yum this afternoon, 10 out of 15 seconds were taken up resolving the IP of download.fedora.redhat.com. Replacing Road Runner's DNS servers with OpenDNS took this down to 5 seconds. Putting OpenDNS before my router's DNS server makes the time negligible.

Anyways, the details:

  • Copy /usr/share/doc/dhclient-$VERSION/dhclient.conf.sample to /etc/dhclient.conf

  • Edit /etc/dhclient, removing everything before the 'prepend domain-name...' line, and everything after the 'initial-interval 2;' line.

  • On the 'prepend domain-name-servers' line, replace '127.0.0.1' with
    '208.67.222.222 208.67.220.220'.

  • Take down and bring back up your network connection. /etc/resolv.conf should now start with the two 208... IP addresses.


The important part I believe is to keep the 'request' and 'require' bits in dhclient.conf. This setup will play nicely with NetworkManager, too. Mad props to Orangebat for pointing out OpenDNS.

Here's a sample dhclient.conf, to make it easy:

prepend domain-name-servers 208.67.222.222, 208.67.220.220;
request subnet-mask, broadcast-address, time-offset, routers,
domain-name, domain-name-servers, host-name;
require subnet-mask, domain-name-servers;
timeout 60;
retry 60;
reboot 10;
select-timeout 5;
initial-interval 2;

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