Pop quiz: how can one replica break another replica

Suppose you have a MySQL master-slave replication setup. It is very straightforward, nothing exotic at all. Imagine that it is the simplest possible setup. Everything is fine, there is nothing wrong or misconfigured with either server.

Now you add another replica, and replication on your existing replica fails. You did not change anything on your existing replica or master. How did this happen?

I'm Baron Schwartz, the founder and CEO of VividCortex. I am the author of High Performance MySQL and lots of open-source software for performance analysis, monitoring, and system administration. I contribute to various database communities such as Oracle, PostgreSQL, Redis and MongoDB. More about me.