Hi @stephenb ,
Thanks for your response.
I checked the documents again, It seems like "elastic-stack-ca.p12" is the CA and "elastic-certificates.p12" is the certificate issued by CA.
In my case the "elastic-stack-ca.p12" was generated three years ago and the expiration date is Oct 2024. I need to regenerate the CA instead of using the old one because the expiration date will not change if i'm not using the new CA.
I will reference this guideline to regenerate the CA.