Many of us have had the misfortune to experience multiple periods of downtime due to our ISPs DNS servers being poorly maintained. When this happens, the best course of action is to swap your computers DNS settings to a public server such as openDNS or Google Public DNS (If you don’t mind having even more of your browsing data slurped up by the big G).
Since it’s so simple to update your routers DNS settings or even setting them directly on your computer itself, it’s a trivial act to test openDNS. Unless your ISP is particularly small or extraordinarily worse at maintaining their DNS servers than the average ISP, you should find that their resolvers answer much quicker than the free public alternatives. This is because their servers are located physically much closer to your computer. However, speed alone isn’t enough. After all, saving 100ms on a DNS lookup might not be preferred if those servers are down for a couple hours every few days.