System Administrator Job Interview Questions – Part 1

What is Active Directory?

Active Directory is a network-based object store and service that locates and manages resources, and makes these resources available to authorized users and groups. An underlying principle of the Active Directory is that everything is considered an object—people, servers, workstations, printers, documents, and devices. Each object has certain attributes and its own security access control list (ACL).

What is LDAP?

LDAP is an Internet standard protocol used by applications to access information in a directory. It runs directly over TCP, and can be used to access a standalone LDAP directory service or to access a directory service that is back-ended by X.500.

Can you connect Active Directory to other 3rd-party Directory Services? Name a few options.

Yes. Microsoft Identity Integration Server (MIIS) is used to connect Active Directory to other 3rd-party Directory Services (including directories used by SAP, Domino, etc).

Where is the AD database held? What other folders are related to AD?

AD Database is saved in %systemroot%/ntds. You can see other files also in this folder. These are the main files controlling the AD structure

• ntds.dit
• edb.log
• res1.log
• res2.log
• edb.chk

When a change is made to the Win2K database, triggering a write operation, Win2K records the transaction in the log file (edb.log). Once written to the log file, the change is then written to the AD database. System performance determines how fast the system writes the data to the AD database from the log file. Any time the system is shut down, all transactions are saved to the database.

During the installation of AD, Windows creates two files: res1.log and res2.log. The initial size of each is 10MB. These files are used to ensure that changes can be written to disk should the system run out of free disk space. The checkpoint file (edb.chk) records transactions committed to the AD database (ntds.dit). During shutdown, a "shutdown" statement is written to the edb.chk file. Then, during a reboot, AD determines that all transactions in the edb.log file have been committed to the AD database. If, for some reason, the edb.chk file doesn't exist on reboot or the shutdown statement isn't present, AD will use the edb.log file to update the AD database.

The last file in our list of files to know is the AD database itself, ntds.dit. By default, the file is located in\NTDS, along with the other files

References: Google, http://technet.microsoft.com, WikiAnswers.com and various other online and offline resources.