Error 118: how can I check the website is down or up?

Error 118 (net::ERR_CONNECTION_TIMED_OUT): The operation timed out.

While browsing, I encountered this error/problem several times.
1. You may be experiencing issues with your Internet connection.
To check the internet connections problem as guided in error page, I adjusted proxy settings also as:
Go to the wrench menu > Options > Under the Hood > Change proxy settings > LAN Settings and deselect the "Use a proxy server for your LAN" check box.
But the problem was not solved.
2. The website maybe down.
Now the problem is: how can I check the website whether it is down or up.
Can any body tell me what should I do now to solve this problem?
