I don’t often use log4net – at least, I use it on just about every project but I only set it up once every few months – so remembering the schema for the configuration is a drag.  Thankfully, a generous geek has created a schema for the config.  You can get it here.

After you download it, copy it to your Visual Studio Schemas folder.  For VS 08 this is C:\Program Files\Microsoft Visual Studio 9.0\Xml\Schemas.  For 2010, it’s probably C:\Program Files\Microsoft Visual Studio 10.0\Xml\Schemas.

Then with your web.config/app.config open in VS, view the properties and set the schema to include this. 

No need to restart VS, it will automatically detect the new schema in the folder. Intellisense will then tell you all you need to know.