if your ISP have problem with DNS, you can use public dns for name resolution.
Google Public DNS (Recommended)
8.8.8.8 8.8.4.4
http://code.google.com/speed/public-dns/
Level 3 Communications
4.2.2.2 4.2.2.4 4.2.2.6
OpenDNS.com
208.67.222.222 208.67.220.220
To add DNS server, take property of your LAN Card, Click “Internet Protocol (TCP/IP)” click the button property. On next page, you have option to specify your own dns server.