In sharepoint world you should know where the sharepoint database is to trouble shoot database related issues.Some one come to you and say i am getting unable to connect to database error or my sharepoint is down.So you may not know the details of the environment.In first step you need to identify the servers so you have to find the configdb and content db servers.
How to find the Config DB
Configuration database connection string is stored in Registry key. So sharepoint look for that entry to identify the database.
In Sharepoint 2007 you could see the config DB conection string in Following Registry Key
My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\12.0\Secure\ConfigDb
In Sharepoint 2010 you could see the config DB conection string in Following Registry Key
My Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Shared Tools\Web Server Extensions\14.0\Secure\ConfigDb
The Next thing you have to find the Content DB attached to Web application.Here you have to remember one thing a web application could hold multiple site collection.So it will have multiple ContentDB
1. Go to Central Admin
2. Go to Application Management
2. Go to Database section and click on Manage Content Database
3. From the list Select your web Application
4.Click on the content DB it will take to details page.
Content DB details page you could identify the DB Server