Can't access specific websites with Macbook Air (10.7.5 Lion)
For such problem one more option is there where you can check your DNS settings. To fix that problem, open the Network pane of System Preferences and select your network connection in the list on the left. Click Advanced followed by DNS.
In the DNS Servers field, you should see one or more IP addresses. If those addresses are enabled (black, as opposed to gray), select each one in turn and click the minus-sign (-) button. Then, regardless of whether there are already addresses there in gray, click the plus-sign (+) button and enter 208.67.222.220; repeat with 208.67.222.222.
Some more Ipv4 and Ipv6 addresses are given at computerknow.org, you may see there.
I'm in the same boat. I've tried deleting cache and cookies, but it did't work for me. After surfing some websites, I found some tips that worked for me.
- Go to System Preferences,choose network
- Click "advanced", go to the "Hardware" tab, and click on "configure", choose "manually"
- Click on mtu, change it to "custom" and set the mtu number to 1453 (I dont why but the number is something like a networking secret from ancient times)
Here's a solution that helped me - I was desperate as nothing I had done had helped, the problem was only specific to my macbook (other devices connected just fine) and across browsers.
After speaking with three different assistants from Apple Support, the third of which stayed with me on shared screen for over an hour trying to help me resolve this, I bumped into a solution on my own, so I'm sharing it here in case it helps other people:
First back-up (just in case) and then delete the following folder:
/Library/Preferences/SystemConfiguration
Then, reboot (and the system will re-create the folder with default settings.)
You will have to enter your network's credentials again (password etc).
It worked for me.
Before that I couldn't access certain google services (youtube, docs, drive) although others worked fine (google.com, gmail.) After this, I could access everything just like normal.
The weirdest thing was that, I don't remember doing anything in particular that caused this to happen yesterday (when the problems started) so I have no idea what exactly went wrong - all I know was that deleting all the configuration files sorted it out.
Hope this helps!