Exam 300-425 topic 1 question 112 discussion

B answer in incorrect As per Cisco book "The active unit keeps CAPWAP tunnels, AP states, client states, configurations, and image files all in sync with the hot standby unit. If the active unit fails, the hot standby unit quickly takes over the active role"

Only clients that are in Run state are synced between the Active and Standby WLC. Client SSO does not support seamless transitions for clients that are in the process of associating/joining the controller. The clients in the transition phase will be de-authenticated after switchover and will need to rejoin the controller. no deatails about the WLC status in public spaces. in that case we assume that there is no issue with the connetivity between WLCs Round trip latency on Redundancy Link should be less than or equal to 80 milliseconds. Preferred MTU on Redundancy Link is 1500 or above. Bandwidth on Redundancy Link should be 60 Mbps or more.

This is tough - both B and D are valid answers here (typical Cisco SMH).... but I think the key word is "public", which tells me a lot of clients might be in the "WebAuth_Req" state because it's a public space and clients have to authenticate first and Cisco is likely looking for D as the answer.

I'd say the correct answer is D afterall. I do not like B, because in the SSO, the syncing should be transactional - I cannot imagine you can sync half of the database.

Official Cert Guide page 201: The active controller also synchronizes the state of each associated client that is in the RUN state with the hot standby controller. Any client which is not associated or in the RUN state will not show.

typical cisco questions!

I would vote for B. I can't accept if D is correct. Realistically, there would be only few clients (or mostly zero) which are in an interim state such as "WebAuth_Req". Since the question is mentioning half, then lack of a fully replicated database is more probable. A and C can't be right anyway.