If you haven't heard: The Planet a big, big hosting provider from the USA had some unfortunate incident at one of their hosting facility (involving fires, explosions, etc). Fortunately it seems that no actual computing gear was damaged, however it will be some time until they get back 100% online.
In the meantime, if you are wondering if the connection timeout to your favorite site is related to this, head over to domaintools.com and type in the domain in question. Scroll down to
Server Data and if at
IP Location you see
Texas - Dallas - Theplanet.com Internet Services Inc, you got your answer. This is the situation for example with emergingthreats.net.
If you want to do this manually, do an nslookup on the name and check if the IP is in the 126.96.36.199 - 188.8.131.52 range.
PS. I'm not affiliated with domaintools, I'm just a happy customer.