WCCP uses bits to create and distribute buckets. Using MASK assignment, what is the maximum number of bits used?

Question

Options

• A4
• B7
• C8
• D32
• E256

• A
  5% (1)
• B
  74% (14)
• C
  5% (1)
• E
  16% (3)

Explanation

Option B (7 bits) is correct because WCCP v2 MASK assignment allows a maximum of 7 bits to be set in the mask value. These 7 bits are applied to packet header fields (source/destination IP or port) to create up to 2^7 = 128 distinct bucket values for distributing traffic among cache engines.

Why the distractors are wrong:

• A (4 bits): Too few - 4 bits would only yield 16 buckets; the protocol supports more granularity than this.
• C (8 bits): Off by one - a natural guess since 8 bits = 1 byte, but Cisco caps MASK assignment at 7 bits.
• D (32 bits): Likely confused with the size of an IPv4 address (32 bits), not the mask limit.
• E (256): Likely confused with the number of hash buckets in WCCP Hash assignment (256 buckets), not a bit count.

Memory tip: "MASK stops at 7 - one short of a byte." If you remember that MASK is intentionally limited below a full byte, you'll avoid the tempting 8-bit answer. Alternatively, associate WCCP's two methods: Hash = 256 buckets, Mask = 7 bits max.

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