A data center has a 10 Gbps Direct Connect dedicated connection in us-west-1 attached to a Direct Connect gateway. From the same location there are two private VIFs attached to the same Direct Connect gateway. VIF 1 advertises 172.16.0.0/16 with an AS_PATH of 65000. VIF 2 advertises 172.16.1.0/24 with an AS_PATH of 65000 65000 65000. For traffic whose destination is in 172.16.1.0/24, which VIF will AWS use to route the traffic to the data center?

AWS prefers routes with the shortest ASPATH. VIF 2 advertises the 172.16.1.0/24 route with an ASPATH of 65000 65000 65000 (length 3). VIF 1 advertises the broader 172.16.0.0/16 route, which encompasses 172.16.1.0/24, with an ASPATH of 65000 (length 1). However, for specific traffic destined for 172.16.1.0/24, AWS prioritizes the most specific route. Since VIF 2 offers the more specific /24 route, it will be preferred over VIF 1's less specific /16 route, even though VIF 1 has a shorter ASPATH. Route specificity (longest prefix match) takes precedence over ASPATH length in BGP route selection. Round-robin or flow control routing are not standard BGP behaviors for a single destination prefix.