Are Twitter or other social networking sites suddenly being blocked by OpenDNS on your network?
If you administer your own network and you run into a situation like this (like I did last night on my home network) it’s likely this is the cause.
Most ISP’s will give you a dynamic IP address. This means your IP address changes from time to time. If you end up with an IP address of someone who was also using OpenDNS, you will also get their OpenDNS settings. This seems like a pretty big flaw in OpenDNS’s implementation of configuration options. I’m sure that consumer ignorance plays a big part here, but it seems that this is designed in a way that doesn’t safeguard against this well enough.
My “quick fix” solution was to switch to Google DNS, but I may look into other options when I have time. Suggestions?