Hosting reliability depends on the service and support provide by a host. Reliability of web hosting company also refers to the uptime of their server.

Many hosting companies announce 99.99% uptime and 100% uptime but it not feasible because in year server need maintenance, sometimes internet working very slow that may also cause down time. So, 100% and 99.99% uptime guaranteed is not practically possible.

Many cheap web hosting companies do not have T3 internet line and the lower line will cause slower connection to your web site. So, reliability of web hosting company also depends on the speed of the internet.

Also, the reliability of web hosting company depends on many other factors like system configuration, hardware, software, etc.

Once you have decided to go with one web hosting company you should ask them for the list of the web sites that hosted on their server. Now, directly contact the web site owner and ask him about the service. By this way you will have exact idea about the hosting company reputation in market.

Also, you can ask their technical support team for some features that you unable to find on hosting company website and check the response time of the customer support executive, by this way you can also check how is there technical staff.