2.3 Describe BGP Path Selection Algorithm. 350-501 Practice Questions (Page 1)

Questions 1–5

1. 1expert · hard

   An enterprise AS has two eBGP peers, Peer X and Peer Y, both advertising the same prefix. The network administrator wants all outbound traffic for this prefix to prefer Peer X. The administrator has configured local preference 200 on routes from Peer X and local preference 100 on routes from Peer Y. However, the administrator also configured weight 150 on routes from Peer Y. Which path will be selected?

   • APeer X, because it has a shorter AS path
   • BPeer X, because it has a higher local preference
   • CBoth paths will be load-balanced
   • DPeer Y, because weight is evaluated before local preference
   Reveal Solution Discussion Select an answer first
2. 2foundation · easy

   In BGP path selection, how are eBGP-learned paths treated compared to iBGP-learned paths?

   • AeBGP paths are preferred over iBGP paths
   • BiBGP paths are preferred over eBGP paths
   • CThey are treated equally
   • DThe preference depends on the IGP metric
   Reveal Solution Discussion Select an answer first
4. 3foundation · easy

   What is the primary purpose of the Multi-Exit Discriminator (MED) attribute?

   • ATo prefer routes with a longer AS path
   • BTo influence inbound traffic from a neighboring AS
   • CTo influence outbound traffic from the local AS
   • DTo set the administrative distance for BGP routes
   Reveal Solution Discussion Select an answer first
5. 4application · medium

   A router has two iBGP paths to the same destination. Both paths have identical weight, local preference, AS path length, origin, and MED. The next hop for Path A is reachable via an OSPF route with metric 100, and the next hop for Path B is reachable via an OSPF route with metric 200. Which path will be selected?

   • ABoth paths will be load-balanced
   • BPath B, because it is the oldest route
   • CPath B, because it has a higher IGP metric to the next hop
   • DPath A, because it has a lower IGP metric to the next hop
   Reveal Solution Discussion Select an answer first
6. 5application · medium

   An enterprise AS has two eBGP peers, Peer X and Peer Y, both advertising the same prefix 203.0.113.0/24. The AS path via Peer X is 65001 65002, and via Peer Y it is 65001 65002 65003. The network administrator wants all outbound traffic for this prefix to use Peer X. Both peers are in the same AS and no weight is configured. Which configuration change will achieve this goal?

   • APrepend the AS path on Peer Y
   • BSet a higher local preference on routes learned from Peer X
   • CSet a lower MED on routes learned from Peer X
   • DSet a higher weight on routes learned from Peer X
   Reveal Solution Discussion Select an answer first