Diversity in configuration for web applications makes the testing of these systems very difficult. As discussed, there may be various types of browsers supporting different operating systems, variations in servers, networks, etc. Therefore, configuration testing becomes important so that there is Compatibility between various available resources and application software. The testers must consider these configurations and compatibility issues so that they can design the test cases incorporating all the configurations. Some points to be careful about while testing configuration are:

1. There are a number of different browsers and browser options. The web application has to be designed to be compatible for majority of the browsers.
2. The graphics and other objects on a website have to be tested on multiple browsers. If more than one browser will be supported, then the graphics have to be visually checked for difference in the physical appearance. Some of the things to check are centering of objects, table layout colours, monitor resolution, forms, and buttons.
3. The code that executes from the browser also has to be tested. There are different versions of HTML. They are similar in some ways but they have different tags which may produce different features. Some of the other codes to be tested are Java, JavaScript, ActiveX, VBscripts, Cgi-Bin Scripts, and Database access. Cgi-Bin Scripts have to be checked for end operations and are most essential for e-commerce sites. The same goes for database access.
4. All new technologies used in the web development like graphics designs, interface calls like different API's, may not be available in all the operating systems. Test your web application on different operating systems such as Windows, Unix, MAC, Linux, Solaris with different OS flavors.