Using a public DNS address is a common solution to not hosting your own DNS servers. Public DNS servers are hosted for your use as an alternative method of configuration, public DNS servers also provide a excellent tool for trouble shooting suspected DNS issues.
If your network is experiencing problems reaching the internet the first thing to do would be to check your equipment. If you are connected to the network and cannot reach the internet checking your DNS settings is a good place to begin troubleshooting. For a list of DNS troubleshooting tools click here
Navigate to the following google web site for step by step instructions. http://code.google.com/speed/public-dns/docs/using.html .
I have also created a short version for you here.
Open up the properties dialog of your internet connection Local Area Connection Properties and open IPV4 dialog.
Select the Advanced button select the DNS tab and then click ‘Add’
Inside the DNS server dialog add the Google server address of 188.8.131.52 click Add and then repeat the process adding 184.108.40.206
Click OK then OK then OK again if needed to close the network properties dialog box.
Now close and reopen your internet browser then attempt to go to the web site that would not open previously.