A few way could solve it
1. Controlling your emulator DNS
Use -dns-server X.X.X.X when you start up your emulator regardless from Eclipse or SDK Manager http://developer.android.com/guide/developing/tools/emulator.html
2. Disable interfaces
Disable any network interface that are not using and restart your PC.
3. Disable and reenable your network interface
This may help your emulator to update the DNS server list it is using.
4. Flush your system DNS cache
At cmd, type ipconfig /flushdns
5. Check your DNS setting at your network adaptor
By using Windows Resource Monitor, you can see what DNS server is your emulator using. Check the DNS server validity. If necessary, change the DNS server setting at your network adaptor. Make sure the valid DNS server is at the top of the DNS server list as the Emulator may only read the first DNS on the list.