For shared key authentication, which of the following description is wrong?

Question

Options

• AAfter using shared key authentication, WEP encryption must be used
• BShared key requires user and AP to use the same shared key
• CFor thin APs, the shared key is pre-set in the AC
• DThe disadvantage of the shared key is that it has poor scalability and is not very secure

• A
  4% (1)
• B
  8% (2)
• C
  77% (20)
• D
  12% (3)

Explanation

Option C is the wrong statement because in a thin AP deployment, the shared key is not "pre-set" (factory-configured by default) in the AC. Instead, an administrator must manually configure the shared key on the AC, which then distributes that configuration to the thin APs. Calling it "pre-set" incorrectly implies it comes ready-to-use without administrative input, which would also be a security risk.

Option A is correct: shared key authentication is built on the WEP protocol - it works by having the AP send a plaintext challenge that the client encrypts using the shared WEP key, so WEP encryption is inherently required. Option B is correct: the entire mechanism depends on both the client and AP holding an identical key, which is what makes it "shared." Option D is correct: because keys must be manually distributed and configured on each device, shared key authentication scales poorly for large networks and WEP itself is cryptographically broken, making it both an operational and security liability.

Memory tip: Think of "pre-set" as the trap word. In thin AP architecture, nothing meaningful is pre-set - the AC is the central brain that an admin must program, and it then instructs the APs. If a statement implies a key or credential is already there without admin action, treat it with suspicion.

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