In case you haven't heard, Anonymous plans to shutdown the internet March 31 to protest a multitude of issues which I'm not going to bother to get into right now.
The plan is to attack all 13 root DNS servers with Denial of Service (DoS) attacks.
By shutting down all 13 root DNS servers, a domino effect will be felt throughout the internet and eventually all DNS queries will begin to time out.
Their plan is pretty bold, and will require a tremendous number of computer systems attacking at once.
While it is unknown if Anonymous' plan can succeed, there are a few things you can do to mitigate this threat from affecting your organization.
1) Don't panic. This shutdown is on a Saturday, so the number of employees this affects will be minimal. If your organization isn't even open on Saturdays, then this won't affect your organization at all.
2) If you are open on Saturday, consider putting one of your local DNS servers in caching mode if it isn't already, and increase the DNS caching time to live (TTL) to 86400 seconds (24 hours). Any commonly used sites should remain cached throughout the attack. It's a good idea to revert to your original settings Monday morning.
3) Finally, if you absolutely must have access to certain websites with static IP addresses, such as business partners or suppliers, consider making available to your on-call support staff a hosts file with critical domain names and IP addresses pre-loaded, so that they can drop this file on any organizational systems which start to have DNS problems. Once again, revert to your original settings Monday morning.
These three simple tips should help keep your organization up and running, should Anonymous actually succeed in taking down one or more root DNS servers.
For home users, I would recommend checking your local weekend weather forecast Friday evening. If it's going to be nice out, be ready to go outside for a change, get some exercise and have some fun. If not, consider breaking out some board games for the kids, or find yourself a nice book to read. It's only one day, if it even happens, and it's not the end of the world.