I was having problems with my ISP’s DNS servers so I decided to set them manually to those from OpenDNS rather than relying on DHCP to set them automatically.
Edit /etc/conf.d/net (on Gentoo Linux) and set the following lines:
dhcp_eth0="nodns"
dns_servers_eth0="208.67.222.222 208.67.220.220"
Change eth0 to the name of your network interface, also change the IPs to whichever OpenDNS are using at present (they should be listed on their home page).
