Possible Internet Outage???...Need Web Expert

Okay, here's the situation which finally been corrected no thanks to me.

I was online this morning and at about 8:45 my I lost my Internet connection.

I replugged back in my cable modem and noticed that the lights didn't come
back on all the way, meaning that my cable company (Comcast) was down
or they had an outage someplace. Okay, fine.

About an hour later, the service came back on and I was able to connect.

However, two sites that I normally go to would not come up. I was getting
that could not connect message.

The two sites were:

http://twitter.com/home

https://www.clickbank.com/login.htm

Since I was able to connect with every other site on the Internet that I
normally go to during my day, I found this odd. What were the chances
that both of these sites would be down at the same time?

Eventually, they both came back up...and at the same time.

After doing some thinking, trying to figure this out logically, I came up
with several possible causes.

1. The 2 sites just happen to both be down. Not impossible, but both come
back up at the same time?

2. They were down because they were on the same route or server or
whatever path and access to that path was down through my company
still.

3. Same as number 2 but path down to the entire Internet, meaning not
only couldn't Comcast customers connect but nobody could. I don't even
know if this is possible.

4. The problem was in my machine. Doubtful since I didn't do anything to
fix the problem. It just fixed itself.

If somebody can please explain how this could happen? Is it one of the 4
things above or something I'm not accounting for?

Any help to explain this to me will be appreciated so that the next time
this happens I have an idea of what's going on and won't look for trouble
in places where it doesn't exist.

Thanks.