Your manager has asked you to check the index stats for a particular table called Address. You
have executed the following query (see below) and it reported that the
avg_fragmentation_in_percent is 15%. What should you do?
SELECT * FROM sys.dm_db_index_physical_stats (DB_ID(N’Test’),
OBJECT_ID(N’Address’), NULL, NULL , ‘DETAILED’);

A.
Run ALTER INDEX REBUILD WITH (ONLINE = ON)

B.
Run ALTER INDEX REORGANIZE

C.
Rebuild the table

D.
Nothing, the index fragmentation is at a safe level

Explanation:
Generally, you should reorganize indexes if the fragmentation is between 5 and 30 percent. You
should rebuild the index if the fragmentation is over 30 percent. Remember, these values provide
a rough guideline for determining the point at which you should switch between ALTER INDEX
REORGANIZE and ALTER INDEX REBUILD. However, the actual values may vary from case to
case. It is important that you experiment to determine the best threshold for your environment.