Transparent Network Substrate

TNS is sort of like DNS for Oracle. In TNS one defines aliases which map to collections of settings that specific certainly both the hostname to connect to and the particular database at the server to dive into there and also possibly some other settings like port numbers. When making a connection in Oracle one will often just give an alias, a username, and a password. All the guts of what might be in an MSSQL connection string beyond how one authenticates need not be exposed in Oracle.