How to conduct employee reference & performance check with previous boss?

Some tech firms ask for references but hardly check/give them a call. In others, the recruitment team is asssigned the task of checking the candidate performance and other details, there are 2 parts of the reference check discussion. We can call it Validation and Verification. Here are the 5 questions that can be used for reference check discussions.

Checklist for reference check discussion

Firstly the call to the reference is a professional discussion with a person who could be busy at work or who wants to give recommendation for a peer developer. So first question is to check if they got time to answer your questions. Here are the questions

1. What is your professional relationship with the job seeking candidate?
2. What are the strengths of the candidate?
3. What are the weakness of the candidate?
4. What are the key achievements of the candidate?
5. Rate verbal and written communication skills of the candidate?
6. Would you rehire the candidate if given a chance?
7. Any closing comments on the candidate?