A couple of days ago, I was talking to a friend who is running a small office in NY. He complained about how they were frequently having issues accessing web sites, the sluggishness and the inconsistencies they were experiencing.
The more we talked, the more it sounded like taking a look at their DNS servers was in order. They did not, however, have a dedicated DNS, and were using whatever DNS servers their ISP was assigning to them.
Google's Public DNS is probably the most famous one and I fully recommend it. Open DNS is another one that has been out there for a while.
Not only using public DNS may improve the speed of your browsing but it may also help you get a little extra security.
I recently came across a little (literally - just 163KB) utility called DNS Benchmark by Steve Gibson which can tell you which name servers would be the fastest for you.
As I guessed, Google's Name Servers, which I have been using for quite some time now were the fastest for me. In my case, it was not the name resolution speed that pushed me to switch to Public DNS. I hated it when my ISP intercepted mistyped domain names. If you do that, you should normally get a "404 - Page not found" error. Instead, you notice that the url you typed is put into a search web site branded by your ISP and results are shown to you.
ISPs are not really doing this out of goodwill to help you, they get money out of it. They get paid for the keywords and appropriate results show up near the top. You can read about that whole story and how that is being used for Phishing attacks here.
Here is the screenshot from my LinkSys (Cisco) E3000 router.
In most cases, you can reach your router's set up by typing 192.168.1.1 into your browser and logging into it. The settings you see above are located under "Setup" > "Basic Setup".
By the way, if you are using Google Chrome, it is up to you to choose whether Google should display you some suggestions when you mistype a url or a domain name. Here are instructions to turn on or off this option. Good luck!