Friend I am very happy to see your participation here and you explain each question in a good way. I agree with you that at 24th of March in 2016 it was the birth or beginning of the blockchain we can see by reading history of this blockchain which is very interesting also.

You calculate age in a right way as well as you have explained that what is down time and it is the Mal functioning or disturb functioning of a blockchain as well as you have also explain that why it can occur and you relate down time with this blockchain in a good way over all a nice post with a nice presentation I see from you I wish you success