Configuring Master Pages

So far, you've used the master attribute of the Page directive in the content pages to specify the name of the master page. Even though this approach works, it requires you or your developers to specify the master attribute in each page. You can eliminate that requirement by specifying the name of the master file in the web.config file under the pages element. After adding the entry to your web.config file, all the pages in that Web application will automatically use the designated master page. For example, the following web.config file entry specifies that all the pages in the Web application should use IntroMaster.master as their default master page.







You're not limited by setting the default master page in the web.config file. Even when you use this method to specify the name of a default master page, you can still override the global value by specifying a different master page in the master attribute of the Page directive. Any values you specify using the Page directive takes precedence over the web.config file entry.

To sum up, ASP.NET's new Master Pages feature provides a clean approach to encapsulate common functionality and content a centralized location, allowing other pages to inherit from those master pages, thereby greatly reducing the maintenance. Using master pages, you can also create one set of controls and code and apply the results to all your content pages. Apart from providing a fine-grained control over the layout of the content pages, master pages also expose an object model that allows you to access the master page controls, properties and methods from content pages.

ref:devx