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350-401 · Question #1258

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

The correct answer is D. TCAM entries are composed of value, mask, and result, and MAC address table entries are. The fundamental architectural difference lies in how each memory type stores and processes entries for lookups.

Submitted by devops_kid· Mar 6, 2026Infrastructure

Question

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

Options

  • ATCAM entries are stored for 600 seconds, and MAC address table entries are kept for 200
  • BTCAM entries are populated using the ARP table, and the MAC address table is populated
  • CTCAM entries consist of VLAN, port ID and source MAC Address, and MAC address table entries
  • DTCAM entries are composed of value, mask, and result, and MAC address table entries are

How the community answered

(48 responses)
  • A
    2% (1)
  • B
    4% (2)
  • C
    6% (3)
  • D
    88% (42)

Why each option

The fundamental architectural difference lies in how each memory type stores and processes entries for lookups.

ATCAM entries are stored for 600 seconds, and MAC address table entries are kept for 200

Aging timers for MAC address table entries are typically 300 seconds by default, and TCAM entries are not aged in the same time-based manner as MAC addresses, so this choice incorrectly defines the aging mechanisms and values as a primary architectural difference.

BTCAM entries are populated using the ARP table, and the MAC address table is populated

MAC address tables are populated by learning source MAC addresses from incoming frames; ARP tables map IP to MAC addresses, which is a different function, and TCAM is used for policy-based lookups, not directly populated by ARP.

CTCAM entries consist of VLAN, port ID and source MAC Address, and MAC address table entries

While MAC address table entries include MAC address, VLAN, and port, TCAM entries are more generalized for flexible policy matching using value, mask, and result, not limited to these specific components.

DTCAM entries are composed of value, mask, and result, and MAC address table entries areCorrect

TCAM (Ternary Content Addressable Memory) entries are composed of a value, a mask, and a result, allowing for 'don't care' bits and enabling complex, multi-field lookups used in ACLs, QoS, and routing. In contrast, a MAC address table (CAM) stores exact MAC address-to-port mappings, performing an exact match lookup for Layer 2 forwarding.

Concept tested: TCAM vs. MAC address table architecture

Source: https://www.cisco.com/c/en/us/products/collateral/switches/catalyst-6500-series-switches/prod_white_paper0900aecd803362a6.html

Topics

#TCAM#MAC address table#switching architecture#value-mask-result

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