Regarding the BGP decision algorithm, two statements that are correct are:
A higher local-preference attribute will be favored over a lower local-preference attribute. The local-preference attribute is used by BGP routers within an AS to indicate their preference for an exit point from the AS. A higher value means a more preferred path. The local-preference attribute is exchanged only between iBGP peers and does not leave the AS boundary89.
A path cannot be considered if the next-hop is inaccessible. The next-hop attribute is used by BGP routers to determine where to forward packets for a given destination prefix. The next-hop attribute is usually set to the IP address of the eBGP neighbor that advertises the prefix. If there is no IGP route to reach the next-hop address, the path is marked as invalid and ignored by BGP1011.
The other two statements are incorrect because:
The most important criteria is not the administrative distance, but rather the weight attribute. The administrative distance is used by routers to choose between routes from different routing protocols, not within BGP. The weight attribute is a Cisco-specific attribute that is used by BGP routers to prefer one path over another within the same router. The weight attribute is local to the router and not advertised to any peers1213.
A lower local-preference attribute will not be favored over a higher local-preference attribute, as explained above.
References: BGP Best Path Selection Algorithm - Cisco, Understanding BGP Local Preference Attribute - NetworkLessons.com, BGP Next Hop Attribute Explained - NetworkLessons.com, BGP Next Hop Processing - Cisco Press, BGP Weight Attribute Explained - NetworkLessons.com, Understanding BGP Weight Attribute - Cisco Community
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