What is the default aging time, in seconds, for entries in the MAC address table on a Cisco Catalyst switch?
- 1200
- 150
- 600
- 60
- 300
Explanation: The MAC address table, often referred to as the Content-Addressable Memory (CAM) table, is the primary database used by a switch to make Layer 2 forwarding decisions by mapping source MAC addresses to specific physical ports. To ensure that this table remains efficient and does not retain information for devices that have disconnected or moved, the switch implements an aging timer for all dynamically learned entries. By default, the aging time on a Cisco Catalyst switch is 300 seconds (5 minutes). If the switch does not receive a frame with a particular source MAC address within this five-minute window, the entry is automatically purged from the table to make room for new information. This value represents a balance between minimizing "unknown unicast flooding" and maintaining an accurate, up-to-date forwarding table. It is important to distinguish this from the "Aging Time" often seen in Spanning Tree Protocol (STP) outputs (such as 15 seconds), which is a shortened timer used only during topology changes to quickly clear stale network paths. While the specific value of 300 seconds is not explicitly stated in the provided excerpts, it is the standard operational default for Cisco Catalyst switches and was previously identified in our conversation history regarding MAC address table management.
Related exam: Modules 1 – 7: Checkpoint Exam: Network Switching Answers (CCNP ENCOR v9)
