Blocked URL's via the DNS-server

This is used for example from some German providers. It is a very cheap and easy censoring method and the same is true for bypassing it.

First, I will explain what the Domain Name System is: Every computer on the Internet has an unique address, a little bit like a telephone number. These are 4 numbers from 0 to 255 separated with a dot. For example: 62.141.48.209 is the IP address for www.freerk.com. Because of remembering such a number is very difficult, the DNS was invented. This service maps an URL to it's IP address. If you type nocensor.freerk.com into your browser, the request is send to the DNS-server that was automatically given to you by your ISP on dialing into the Internet. A lot of addresses are already cached, so the DNS-server sends the IP address for the URL back to you. If the DNS-server has no cached information on the site requested by you, he asks on of the 13 root servers, which know all addresses.

If the DNS-server from your provider is censoring, he just refuse to send you the real IP-address. He sends you nothing or an IP from a "sorry" website.

To bypass this censorship method you can use another DNS server or try other bypass methods.

More info: http://www.encyclopedia-online.info/DNS

Last updated: 2006-01-10