Which of the following is best defined as a circumstance in which a collection of information items is required to
be classified at a higher security level than any of the individual items that comprise it?

A.
Aggregation

B.
Inference

C.
Clustering

D.
Collision

Explanation:
Aggregation is the act of combining information from separate sources. The combination of the data forms new
information, which the subject does not have the necessary rights to access. The combined information has a
sensitivity that is greater than that of the individual parts. Thus the collection/aggregation of data should be
classified at a higher security.
Incorrect Answers:
B: Inference is the intended result of aggregation. The inference problem happens when a subject deduces the
full story from the pieces he learned of through aggregation. This is seen when data at a lower security level
indirectly portrays data at a higher level.
C: The term clustering does not apply here.
D: The term collision does not apply here. In a computer system, a cluster is a group of servers and other
resources that act like a single system and enable high availability.

Conrad, Eric, Seth Misenar and Joshua Feldman, CISSP Study Guide, 2nd Edition, Syngress, Waltham, 2012,
p. 1183