This is kinda new but all over the world now powerful corporations are fighting to have control over what you can see on the internet.
Typical examples are the recent blockings of ThePirateBay is european countries such as Belgium and The Netherlands.
One is just DNS based, the other is DNS and IP based.
Here you'll find a few guides to help you with that depending on the situation you're in:
- DNS Censorship (example: ThePirateBay in Belgium)
- DNS and IP Censorship (example: ThePirateBay in the Netherlands)
How do you know which case if for you ? Well ... If you're not a technical user , just try the first article and if it doesn't work , hop on to the second article.