Explanation

* Correct answer is To directly reference one shared and customized log4j2.xml file from multiple Mule applications. Key word  to note in the answer is directly.

* By default, CloudHub replaces a Mule application's log4j2.xml file with a CloudHub log4j2.xml file. This specifies the CloudHub appender to write logs to the CloudHub logging service.

* You cannot modify CloudHub log4j2.xml file to add any custom appender. But there is a process in order to achieve this. You need to raise a request on support portal to disable CloudHub provided Mule application log4j2 file.

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* Once this is done , Mule application's log4j2.xml file is used which you can use to send/export application logs to other log4j2 appenders, such as a custom logging system MuleSoft does not own any responsibility for lost logging data due to misconfiguration of your own log4j appender if it happens by any chance.

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* One more difference between customer-hosted Mule runtimes and CloudHub deployed mule instance is that

- CloudHub system log messages cannot be sent to external log management system without installing custom CH logging configuration through support

- where as Customer-hosted runtime can send system and application log to external log management system

MuleSoft Reference:

https://docs.mulesoft.com/runtime-manager/viewing-log-data

https://docs.mulesoft.com/runtime-manager/custom-log-appender