Lots of folks having problems accessing sites out of Turkey just now. One solution to to change your DNS settings to those of Google.
Ironically, many of those having problems wont be able to see this...
Here are step by step instructions for Windows 7, for other operating systems see link at bottom of post. Take your time, it looks really complicated but if you take it step by step its pretty straightforward.
When you use Google Public DNS, you are changing your DNS "switchboard" operator from your ISP to Google Public DNS.
In most cases, the IP addresses used by your ISP's domain name servers are automatically set by your ISP via the Dynamic Host Configuration Protocol (DHCP). To use Google Public DNS, you need to explicitly change the DNS settings in your operating system or device to use the Google Public DNS IP addresses. The procedure for changing your DNS settings varies according to operating system and version (Windows, Mac or Linux) or the device (computer, phone, or router). We give general procedures here that might not apply for your OS or device; please consult your vendor documentation for authoritative information.
Important: Before you startBefore you change your DNS settings to use Google Public DNS, be sure to write down the current server addresses or settings on a piece of paper. It is very important that you keep these numbers for backup purposes, in case you need to revert to them at any time.
Example: Changing DNS server settings on Microsoft Windows 7
Go the Control Panel.
Click Network and Internet, then Network and Sharing Center, and click Change adapter settings.
Select the connection for which you want to configure Google Public DNS. For example:
To change the settings for an Ethernet connection, right-click Local Area Connection, and click Properties.
To change the settings for a wireless connection, right-click Wireless Network Connection, and click Properties.
If you are prompted for an administrator password or confirmation, type the password or provide confirmation.
Select the Networking tab. Under This connection uses the following items, select Internet Protocol Version 4 (TCP/IPv4) or Internet Protocol Version 6 (TCP/IPv6) and then click Properties.
Click Advanced and select the DNS tab. If there are any DNS server IP addresses listed there, write them down for future reference, and remove them from this window.
Click OK.
Select Use the following DNS server addresses. If there are any IP addresses listed in the Preferred DNS server or Alternate DNS server, write them down for future reference.
Replace those addresses with the IP addresses of the Google DNS servers:
For IPv4: 8.8.8.8 and/or 8.8.4.4.
For IPv6: 2001:4860:4860::8888 and/or 2001:4860:4860::8844
Restart the connection you selected in step 3.
Test that your setup is working correctly; see Testing your new settings below.
Repeat the procedure for additional network connections you want to change.
Testing your new settings
To test that the Google DNS resolver is working:
From your browser, type in a hostname (such as
http://www.google.com/). If it resolves correctly, bookmark the page, and try accessing the page from the bookmark. If both of these tests work, everything is working correctly. If not, go to step 2.
From your browser, type in a fixed IP address. You can use
http://18.62.0.96/ (which points to the website
http://www.eecs.mit.edu/) as the URL.* If this works correctly, bookmark the page, and try accessing the page from the bookmark. If these tests work (but step 1 fails), then there is a problem with your DNS configuration; check the steps above to make sure you have configured everything correctly. If these tests do not work, go to step 3.
Roll back the DNS changes you made and run the tests again. If the tests still do not work, then there is a problem with your network settings; contact your ISP or network administrator for assistance.
All of the above is from:
Using Google Public DNS where how to change DNS for other operating systems is shown.
JF