Yosemite cannot connect with Google, but with Bing
Assuming you've done this already but just to confirm. This will set you up to use Google's DNS service.


Open the Network pane in System Preferences.
Select the Network connection that is actually in use as indicated by the green dot.
Click Advanced...
Select the DNS tab.
Enter the values from the below screenshot. Take note of anything that is already there under "DNS Servers:" and remove it.
Click on OK to dismiss the Advanced panel and then Apply.


Then try pinging google.com again.