Need to understand Log4Net Configuration section WebForm - asp.net

Question

i was thinking to use Log4Net for our webform application in asp.net. so i checked few article on this but i saw all article not saying about each property regarding configuration.
so i apologized that i have to paste bit big config section here and looking for some one who can help me to understand each property usage.
<?xml version="1.0" encoding="utf-8" ?>
<configuration>
<log4net>
<appender name="DbAppender" type="log4net.Appender.ADONetAppender">
<bufferSize value="0" />
<connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
<connectionString value="{auto}" />
<commandText value="INSERT INTO Log4Net ([date],[thread],[level],[logger],[message],[exception]) VALUES
(#log_date, #thread, #log_level, #logger, #message, #exception)" />
<parameter>
<parameterName value="#log_date" />
<dbType value="DateTime" />
<layout type="log4net.Layout.RawTimeStampLayout" />
</parameter>
<parameter>
<parameterName value="#thread" />
<dbType value="String" />
<size value="255" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%t" />
</layout>
</parameter>
<parameter>
<parameterName value="#log_level" />
<dbType value="String" />
<size value="10" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%p" />
</layout>
</parameter>
<parameter>
<parameterName value="#logger" />
<dbType value="String" />
<size value="1000" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%c" />
</layout>
</parameter>
<parameter>
<parameterName value="#message" />
<dbType value="String" />
<size value="4000" />
<layout type="log4net.Layout.PatternLayout">
<conversionPattern value="%m" />
</layout>
</parameter>
<parameter>
<parameterName value="#exception" />
<dbType value="String" />
<size value="4000" />
<layout type="log4net.Layout.ExceptionLayout" />
</parameter>
</appender>
<root>
<level value="INFO" />
<appender-ref ref="RollingFileAppender" />
<appender-ref ref="DbAppender" />
</root>
</log4net>
</configuration>
please see the above config details and answer each property.
1) why <bufferSize value="0" /> is set to 0 ? when one should set other value to bufferSize property ?
2) <connectionType value="System.Data.SqlClient.SqlConnection, System.Data, Version=1.0.3300.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" />
how do i know what PublicKeyToken value i need to use.
3) what is the meaning of connection string auto <connectionString value="{auto}" /> ?
4)
what is the meaning of conversionPattern or
5 what is ExceptionLayout <layout type="log4net.Layout.ExceptionLayout" />
6) what is the meaning of below xml
<root>
<level value="INFO" />
<appender-ref ref="RollingFileAppender" />
<appender-ref ref="DbAppender" />
</root>
what is RollingFileAppender ?
what is DbAppender ?
please discuss about my each point & question. thanks

Answer 1

1/ bufferSize <= 1 means no buffering. Log is written instantly to the database.
http://logging.apache.org/log4net/release/sdk/log4net.Appender.BufferingAppenderSkeleton.BufferSize.html
2/ PublicKeyToken is not Log4net related. Have a look. Keep the given token.
3/ {auto} in connectionString seems to be custom code, maybe taken from here
4/ List of conversion patterns
5/ Exception layout: only the exception text from the logging event will be logged.
http://logging.apache.org/log4net/release/sdk/log4net.Layout.ExceptionLayout.html
6/
FileAppender -> log to file.
RollingFileAppender -> log to file with rotating logs (max N files of length L, then they are erased).
DbAppender -> log to database, that's why there is a connectionString.
More info: http://logging.apache.org/log4net/release/config-examples.html