How to block websites?

[sundol]

How can I do followings?

1. How can I block a site? e.g. http://a.example.com

2. How to block all http://*.example.com except http://exception.example.com ?

[Steve1961]

It might be worth looking at the opendns website. If you create an account with them you get a handy control panel for whitelisting and blacklisting sites.

[iponeverything]

an easy way is just add them your /etc/hosts

with a bogus address.