How microservices communicate with each other and how to handle fault tolerance?

PRIOR KNOWLEDGE ON SPRINGBOOT MICROSERVICES REQUIRED

Based on below papers we have to write systematic Research paper (sample paper attached )

Add these questions in paper

Q1 : what are the factors to be noted while creating microservices?

Q2 : How microservices communicate with each other and how to handle fault tolerance?

Q3 : Challenges in Authenticating and Authorizing microservices?

Papers as below:

Note: As per the document attached need Side headings and proper content : Introduction, Systemtic review with Questions as above, conclusion etc… Every content should be from above mentioned papers only