What is the difference between the MAC address table and TCAM?

Question

Options

• AThe MAC address table supports partial matches. TCAM requires an exact match.
• BThe MAC address table is contained in TCAM ACL and QoS information is stored in TCAM.
• CRouter prefix lookups happen in TCAM. MAC address table lookups happen in TCAM.
• DTCAM is used to make L2 forwarding decisions. CAM is used to build routing tables

• A
  3% (1)
• B
  91% (29)
• D
  6% (2)

Explanation

MAC Address Table vs. TCAM Explained

Option B is correct because the MAC address table is actually stored within the CAM (Content Addressable Memory) portion of a switch's hardware, while TCAM (Ternary CAM) is a specialized extension used to store ACL (Access Control List) and QoS information - this distinction reflects how different forwarding and policy decisions are handled at the hardware level.

• Option A is wrong because it reverses the logic - standard CAM requires exact matches (binary 0s and 1s), while TCAM supports partial matches using a third state (wildcard/mask), which is precisely why it's used for ACLs.
• Option C is wrong because it incorrectly states that MAC address table lookups happen in TCAM; MAC lookups use standard CAM, while router prefix lookups use TCAM.
• Option D is wrong because it swaps the roles - CAM is used for L2 (MAC) forwarding decisions, and TCAM (not plain CAM) is associated with routing and policy decisions.

Memory Tip: Think of TCAM = "Ternary = Three states = Complex rules" - the complexity of ACLs and QoS policies needs that third "don't care" state, while simple MAC lookups only need basic CAM's exact-match binary lookup.

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