For instance, you are trying to reach a website but it is continuously not responding. Their are two posiblities, one is that server of that website is down and the other reason could be that your browser or internet connection is facing problem while performing the process.
Lets try some methods to figure out the right cause. Downforeveryoneorjustme.com is a website that can prove handy. Here, enter the URL and click "or just me". In a second or two status of website will be displayed.