In a hierarchical PKI the highest CA is regularly called Root CA, it is also referred to by which one of thefollowing term?

A.
Subordinate CA

B.
Top Level CA

C.
Big CA

D.
Master CA

Explanation:
Public key infrastructure (PKI) consists of programs, data formats, procedures, communication protocols,
security policies, and public key cryptographic mechanisms working in a comprehensive manner to enable a
wide range of dispersed people to communicate in a secure and predictable fashion. In other words, a PKI
establishes a level of trust within an environment. PKI is an ISO authentication framework that uses public key
cryptography and the X.509 standard.
Each person who wants to participate in a PKI requires a digital certificate, which is a credential that contains
the public key for that individual along with other identifying information. The certificate is created and signed
(digital signature) by a trusted third party, which is a certificate authority (CA).
The certificate authority (CA) is the entity that issues the certificates. CA’s are often organized into hierarchies
with the root CA at the top of the hierarchy and intermediate or subordinate CA’s below the root. As the root CA
is ‘top of the tree’, it is often referred to as the Top-Level CA.
Incorrect Answers:
A: A Subordinate CA is below the root or top-level CA.
C: A Root CA is not known as a Big CA.
D: A Root CA is not known as a Master CA.

Harris, Shon, All In One CISSP Exam Guide, 6th Edition, McGraw-Hill, 2013, p. 833