During the testing phase of a database deployment, you discover that the database is not accepting external connections. You have verified that the database service is running. What is the most likely culprit?
Firewalls are the most common cause of connection failures after verifying the service is running.
Why this answer
Firewall rules frequently block the default ports (e.g., 3306 for MySQL, 1433 for SQL Server) by default upon OS deployment.