I'm doing a practice CCIE lab and I'm still struggling a little with the BGP best path selection process. Can anyone tell me what path attribute causes the best route to be selected from the following output? Please note that the router with BGP router-id of 220.127.116.11 is a an IBGP peer. The other two are eBGP peers. Also, why does the route with a next hop of 18.104.22.168 have an empty metric attribute and how is this compared to the metrics of zero?