Twenty-five questions covering the whole BGP course. The network is the course lab: AS 64500 with ISP A (64501) and ISP B (64502). Each answer has an explanation and each wrong option says why it does not fit. Defaults are Cisco IOS XE.
1. Which attribute is compared first by Cisco IOS XE when choosing a best path?
2. Two paths tie on weight. One has LOCAL_PREF 200 and a long AS path, the other LOCAL_PREF 100 and a short one. Which wins?
3. Which attribute is sent only to iBGP peers?
4. A route learned over iBGP arrives with next hop 192.0.2.1, which the router cannot reach. What happens?
5. How do you make both company routers prefer ISP A for outbound traffic?
6. What does AS path prepending influence?
7. By default, MED is compared between paths from:
8. An inbound route map has one permit sequence matching a prefix list. A route not on the list is:
9. Which AS-path regular expression matches routes originated in your own AS?
10. Which command applies a changed inbound policy without dropping the session?
11. A route reflector learns a route from a non-client. It sends it to:
12. Two peers propose hold times of 180 and 90 seconds. Which is used?
13. The log shows BADAUTH for a neighbour. The most likely cause is:
14. Which command lists BGP best paths that failed to enter the routing table?
15. A neighbour stays in Active with no messages. Which is the best first check?
16. A company with two ISPs has no outbound filters. What does it become?
17. Which AS-path expression matches routes whose last AS is 64511?
18. aggregate-address 198.51.100.0 255.255.252.0 is configured and only a static route for a /24 inside it exists. The aggregate is:
19. A route has penalty 1600 and is stable for one half-life. Its penalty becomes:
20. With default settings, next-hop tracking starts recalculating after a next-hop route is lost about:
21. The log shows a NOTIFICATION 2/2 sent to a neighbour. What is wrong?
22. R2 learned a route over iBGP from R1. R3 is another iBGP peer of R2. Does R2 advertise it to R3?
23. Two sites share AS 64500 through a provider. Site 2 drops routes from Site 1. Which provider-side setting fixes it?
24. You want other networks to prefer ISP A when reaching your prefix. Where do you configure prepending?
25. An extended ACL used as a BGP distribute list holds a network and what in the second pair of fields?