log4net hierarchy and logging levels

This might help to understand what is recorded at what level Loggers may be assigned levels. Levels are instances of the log4net.Core.Level class. The following levels are defined in order of increasing severity - Log Level.

Number of levels recorded for each setting level:

 ALL    DEBUG   INFO    WARN    ERROR   FATAL   OFF
•All                        
•DEBUG  •DEBUG                  
•INFO   •INFO   •INFO               
•WARN   •WARN   •WARN   •WARN           
•ERROR  •ERROR  •ERROR  •ERROR  •ERROR      
•FATAL  •FATAL  •FATAL  •FATAL  •FATAL  •FATAL  
•OFF    •OFF    •OFF    •OFF    •OFF    •OFF    •OFF

For most applications you would like to set a minimum level but not a maximum level.

For example, when debugging your code set the minimum level to DEBUG, and in production set it to WARN.

DEBUG will show all messages, INFO all besides DEBUG messages, and so on.
Usually one uses either INFO or WARN. This dependens on the company policy.