Roaming switching time is a core indicator that affects the service experience of wireless users during roaming. PMK fast roaming can shorten the roaming delay of 802.1x users and improve the user's…

Question

Options

• AOmitting the key negotiation process
• BOmitting the 802.1X authentication process
• CThe user re-association process is omitted
• DOmitted the 802.1X authentication process and key negotiation process

• A
  15% (4)
• B
  73% (19)
• C
  8% (2)
• D
  4% (1)

Explanation

PMK (Pairwise Master Key) caching works by storing the PMK derived from an initial 802.1X/EAP authentication session. When a user roams to a new AP that already holds the cached PMK, the full EAP exchange with the RADIUS server is bypassed - this is precisely what "omitting the 802.1X authentication process" means, making B correct.

Why the distractors are wrong:

• A is wrong because the 4-way handshake (key negotiation/PTK derivation) is not skipped - it still occurs after presenting the cached PMKID to negotiate session keys.
• C is wrong because the re-association exchange between the client and the new AP still takes place; PMK caching has no effect on that step.
• D is wrong because it incorrectly bundles key negotiation with the authentication skip - only the EAP/RADIUS round-trip is eliminated, not both phases.

Memory tip: Think of PMK as a "pre-cleared passport." You already proved your identity (802.1X), so border control (the new AP) just stamps it and hands you a fresh key (4-way handshake) without calling immigration headquarters (RADIUS server) again.

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