CREST Practitioner Security Analyst (CPSA) Practice

Which description fits the term "autonomous system" in networking?

1. A network controlled by multiple administrators

2. A network with no external connections

3. A network under a single administrative control

4. A network that only operates with internal devices

The correct answer is: A network under a single administrative control

The term "autonomous system" in networking refers specifically to a collection of IP networks and routers under the control of a single organization that presents a common routing policy to the internet. This means that it operates as a distinct unit, managing its own routing decisions independently of other networks. This definition aligns with the concept of a network under a single administrative control, which highlights the essential characteristic of an autonomous system: that it is governed and managed by one entity, enabling consistent policy implementation and route management across all connected devices within that system. In the context of internet routing, autonomous systems communicate using specific protocols, such as BGP (Border Gateway Protocol), to exchange routing information with other networks while maintaining their own internal routing policies. This centralized control allows for better coordination, management, and security measures tailored to the organization's needs. In contrast, the other options do not capture the essence of what defines an autonomous system in networking. For instance, a network controlled by multiple administrators does not ensure a unified routing policy, while a network with no external connections would not qualify as an autonomous system since its primary characteristic is its relation to other systems in terms of routing. Similarly, a network that only operates with internal devices lacks the key element of external communication that defines an autonomous