CREST Practitioner Security Analyst (CPSA) Practice

What is the primary function of the Border Gateway Protocol (BGP)?

1. To facilitate communication within a single autonomous system

2. To enable routing between different autonomous systems

3. To manage local area network traffic

4. To address IP address exhaustion

The correct answer is: To enable routing between different autonomous systems

The primary function of the Border Gateway Protocol (BGP) is to enable routing between different autonomous systems. BGP is classified as a path vector protocol that is fundamental to the operation of the internet, as it manages how packets are routed across multiple networks or autonomous systems (ASes). Each autonomous system is a group of IP networks and routers under the control of one organization that presents a common routing policy to the internet. BGP is crucial because it allows different ASes to communicate and share routing information, which is necessary for ensuring that data can flow across the complex and decentralized structure of the internet. It determines the most efficient paths for data transfer, taking into account the various policies and reachability information related to the ASes involved. In contrast, some of the other choices focus on functions that don't align with the specific purpose of BGP. For instance, facilitating communication within a single autonomous system pertains more to internal routing protocols like OSPF or EIGRP. Managing local area network traffic is usually the domain of protocols that operate within smaller networks, while addressing IP address exhaustion relates to strategies and protocols concerning the allocation and management of IP addresses, rather than routing protocols.