Active Directory employee information

Usually in companies, the employee information is stored on an Active Directory server. So I am guessing when we log on to our machine using ID/pwd, it goes and checks an Active Directory. I am wondering开发者_如何学C why Active directory is so universal in use when storing employee information.

Why not use a db? I am aware theoretically of the differences between AD and DB, but from what I know, I do not see why AD is a natural choice for storing employee information.

Here are some reasons why AD is preferred compared to a Relational Database when storung user data

1. AD is heirarchical so if your data is like an employee record where you have a superior then AD is a natural choice having said that AD schema consists of objectclasses and attributes rather than an a DB's tables. This means it uses objectclass inheritance model which is cleaner than linking multipe tables together.
2. Read performance in AD is faster then DB in most cases. But remember DB is faster in saving data.
3. Data Synchronizatoin happens out of the box and nearly no administration at all.
4. Probaly not related to your question but worth mentioning, AD already has a built in functionalities such as secure storage for hashed passwords, password policies, permissions around password changes and password resets which if you use a DB you have to build this on your own
5. Since AD is LDAP then you dont need database drivers to connect to it.
6. With AD you can have multiple values in one attribute if you do this on a normalized database you have to store each attribute value into multiple table linked to the master table.
7. Schema is standardized in AD so where ever you go it will remain the same

I hope this helps