Phil Wainewright writes:
The service is elegant in its simplicity (and is growing virally see usage chart below). It’s a free-of-charge service (funded by advertising more on that in a moment) that specializes in providing robust DNS lookups. At many ISPs, the domain name look-up servers (DNS) are the neglected poor relations of the infrastructure. Yet they’re a vital component in rapid surfing speeds between sites, because every time you click on a link from one site to another, the first thing that happens is your computer has to look up the IP address on the nearest DNS server. If that server is poorly maintained or overloaded, you’ll sit waiting for the site to come up.
Switching to OpenDNS is simply a matter of going to your router admin page and inserting its IP addresses as your preferred DNS lookup. I found an instant improvement in lookup speeds and, better still, no unexplained outages since then. If a site does happen to be down, then instead of not knowing what’s going on, I get redirected to an OpenDNS search page and that’s how the company makes its money, from the ads on the search page when a domain won’t resolve. (It also offers other useful services, like barring known phishing sites and correcting common mistypes, such as skipping the ‘o’ when typing ‘.cm’.