Exhibit:
The best path from Certkiller 18 (AS 65103) to the 172.0.0.0/8 prefix (AS 65101) is _______.
A.
Via Certkiller 15 to AS 65104 then to AS 65101 because it has the best MED.
B.
Via Certkiller 17 to AS 65102 then to AS 65101 because it has the best MED.
C.
Load balanced between Certkiller 15 and Certkiller 17 due to the equal AS-Path length.
D.
Via Certkiller 15 to AS 65104 then to AS 65101 because it has the best Local Preference.
E.
Via Certkiller 17 to AS 65102 then to AS 65101 because it has the best Local Preference.
Explanation:
BGP selects routes based on Higher Local Preference and then lower MED. LP is use to route to a designation. MED is used for path back.Wrong Answers
1. A MED is not used for path there
2. B MED is not used for path there
3. C Not load balanced because Local Preference takes precedence. BGP only hand over best path to IP by default. multi-path would have to be specified for the chance to load balance
4. E Best local preference is the one with the highest value.