Which of the following descriptions about N+1 backup is correct?

Question

Options

• AThe models and software versions of the active and standby ACs must be exactly the same.
• BThe product models of the active and backup ACs can be different, but it is recommended to ensure that the software versions of the ACs are consistent.
• CN+1 backup can also provide backup services for multiple APs, thus saving the cost of purchasing equipment, and the reliability is higher than VRRP dual-machine hot backup.
• DN+1 backup can back up and backs up AP information and STA information.

• A
  8% (3)
• B
  84% (32)
• C
  3% (1)
• D
  5% (2)

Explanation

Option B is correct because N+1 backup in wireless AC (Access Controller) redundancy does not require identical hardware models between the active and standby ACs - different product models can interoperate. However, matching software versions is strongly recommended to ensure feature compatibility and a smooth failover experience.

Option A is wrong because it over-constrains the requirement: hardware models do not need to be exactly the same. Only software version consistency is advised, and even that is a recommendation, not a hard requirement.

Option C is wrong on two counts: N+1 backup is less reliable than VRRP dual-machine hot standby (1:1), not more - one standby AC serving multiple active ACs means a single point of failure for all of them. VRRP provides dedicated per-AC redundancy.

Option D is wrong because N+1 backup synchronizes AP (Access Point) configuration data, but it does not back up STA (Station/client) session information - clients must re-associate after a failover, which is a key limitation compared to hot standby solutions.

Memory tip: Think "N+1 = flexible boxes, same software." The "N" reminds you that multiple different-model ACs can share one standby - hardware flexibility is the whole point - but software consistency is the glue that holds the failover together.

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