MongoDB
A document oriented database classifies as a NoSQL database. Nagios XI can monitor MongoDB Servers as well as MongoDB databases.

MSP
MSPs (Managed Service Providers) are companies that provide outsourced monitoring / management of computer and network services for their clients’ remote networks. MSPs sometimes have VPN connections to their remote clients, but may need an agent like NCPA to effectively monitor machines behind a NAT.

MSSQL
Microsoft SQL Server (MSSQL) is Microsoft’s commercial database.

MySQL
Open Source database. XI uses MySQL as a database backend and can monitor MySQL databases.