The BGP local-preference attribute is used within an Autonomous System (AS) to influence the preferred exit point for outbound traffic. The BGP path selection algorithm prefers the path with the highest local-preference value. The default value in Junos OS is 100.

To make Provider A the primary path, routes learned from R1 must have a higher local-preference than routes from R2. This can be achieved in two ways:

1. Increase the local-preference on routes learned from Provider A via R1 to a value greater than 100.

2. Decrease the local-preference on routes learned from Provider B via R2 to a value less than 100.

Both methods ensure that routes pointing towards R1 are preferred by all iBGP speakers within AS 65000.

B. Use a routing policy to set the local preference attribute value higher for the routes that are learned by R2.

This would incorrectly make Provider B the primary path, as a higher local-preference is preferred.

D. Use a routing policy to set the local preference attribute value lower for the routes that are learned by R1.

This would incorrectly make Provider A the backup path, as a lower local-preference is less preferred.

1. Juniper Networks TechLibrary, BGP Path Selection. This document outlines the BGP decision process. The very first step listed is: "1. Prefer the path with the highest LOCALPREF value." This confirms the fundamental principle that a higher value is preferred, supporting the logic for both correct answers.

Source: Juniper Networks, "BGP Path Selection," Junos OS Documentation.

Reference: Section: "BGP Path Selection on a Routing Device"

2. Juniper Networks TechLibrary, Example: Configuring BGP Local Preference. This configuration example demonstrates a scenario identical to the question, where an import policy is used to set a higher local-preference (e.g., 200) for routes from the primary ISP. This directly validates option A.

Source: Juniper Networks, "Routing Policies, Firewall Filters, and Traffic Policers Feature Guide for Routing Devices," Junos OS Documentation.

Reference: Section: "Example: Configuring BGP Local Preference"

3. Juniper Networks TechLibrary, Understanding BGP Path Selection. This guide explains the role of attributes in path selection. It states, "The local preference attribute provides a mechanism to give iBGP peers a preference for a particular exit point from the local AS." This confirms that local-preference is the correct attribute for this scenario. The same logic of preferring higher values means that lowering the value on the non-preferred path (Option C) is also a valid method.

Source: Juniper Networks, "BGP Feature Guide for Routing Devices," Junos OS Documentation.

Reference: Section: "Understanding BGP Path Selection," Subsection: "Local Preference"