Test on BGP Path Selection and Attributes
BGP Path Selection and Attributes: The Ultimate Guide
Test: BGP
20 questions
Question 1: BGP weight is exchanged between BGP routers.
A. Ano
B. Ne
Explanation: Weight is a Cisco proprietary BGP attribute that is only local to the router and is not exchanged between BGP routers.
Question 2: BGP determines the best path by examining a list of BGP attributes from top to bottom when multiple paths to a destination are available.
A. Ano
B. Ne
Explanation: BGP path selection determines the best path when multiple paths are available by going through a list of BGP attributes from top to bottom. The path with the best attribute is selected. If there is a tie, it moves to the next attribute in the list until a best path is found.
Question 3: The BGP local preference attribute has a default value of 0.
A. Ano
B. Ne
Explanation: The study materials state that the default value for local preference is 100, not 0.
Question 4: BGP's approach to selecting the best path differs from how Interior Gateway Protocols (IGPs) determine the best path, with IGPs typically prioritizing the lowest metric.
A. Ano
B. Ne
Explanation: The study materials state that 'BGP’s path selection is different from how IGPs choose the best path. IGPs choose the best path based on the lowest metric.' Examples provided for IGPs include RIP selecting the lowest hop count and OSPF selecting the lowest cost.
Question 5: When BGP is determining the best path, it evaluates the 'Shortest IGP path to BGP next hop' attribute before considering the 'Local Preference' attribute.
A. Ano
B. Ne
Explanation: The BGP path selection process evaluates attributes in a specific order. 'Weight' is checked first, followed by 'Local Preference'. The 'Shortest IGP path to BGP next hop' attribute is evaluated much later in the list, after several other attributes, including 'Local Preference'.