Two iBGP peers advertise the same prefix into an AS. Route A has local-preference 200, Route B has local-preference 100; all other attributes equal. Which route will the local router select?

BGP path selection prefers the route with the highest Local Preference. In this scenario, Route A has a Local Preference of 200, which is higher than Route B's Local Preference of 100. Therefore, the local router will select Route A. Local Preference is a well-known discretionary BGP attribute used within an Autonomous System (AS) to influence outbound traffic. The other options are incorrect because they represent later steps in the BGP path selection process. The AS path length is considered after Local Preference, and a shorter AS path is preferred. The Multi-Exit Discriminator (MED) is considered even later, typically when comparing routes from different external ASes, and a lower MED is preferred. The numerically lower neighbor IP is a tie-breaker used much further down the path selection algorithm, after many other attributes have been evaluated.