I ran my non-authoritative DNS server [bind] on a droplet for about a year. But the server crashed every few months. Why? Never figured out. A restart always fixed it.
Later shifted to DO's DNS servers.
Now that that one is down too, just shifted back to domain register's DNS.
Later shifted to DO's DNS servers.
Now that that one is down too, just shifted back to domain register's DNS.
Everything is working now.