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Zorluk: OrtaLayer 2 Security Features (Port Security, DHCP Snooping, DAI)

A network administrator configures port security on access interface GigabitEthernet0/10 of a Cisco Catalyst switch using the command `switchport port-security mac-address sticky`. Over the next week, several workstations connect to the port, and their MAC addresses are dynamically added to the running configuration. Following an unscheduled power outage and switch reboot, the administrator discovers that the connected workstations are unable to gain access and port security sticky entries are missing from the configuration. What was the root cause of this issue?

  1. The administrator did not save the running configuration to the startup configuration after the sticky MAC addresses were learned.Cevap
  2. B
    The port security violation mode was left at its default setting of restrict instead of protect.
  3. C
    A native VLAN mismatch occurred between the access interface and the connected workstation network interface card.
  4. D
    PortFast was enabled on the access interface, which automatically clears sticky MAC tables during port state changes.

Cevap

The administrator did not save the running configuration to the startup configuration after the sticky MAC addresses were learned.
When port security is configured with the sticky keyword, dynamically learned MAC addresses are converted into static-like entries and placed directly into the running configuration in RAM. Because RAM is volatile memory, any dynamic sticky entries learned while the switch is operational will be completely lost upon a switch reboot unless the administrator manually executes `copy running-config startup-config` (or `write memory`) to copy the running configuration into non-volatile storage (NVRAM).

Adım Adım Çözüm

1
Analyze how sticky MAC addressing operates in Cisco Port Security.
When `switchport port-security mac-address sticky` is configured, the switch dynamically learns MAC addresses and adds them to the active running configuration file (`running-config`) as static entries.
Understanding where learned sticky addresses are saved during active operation.
2
Evaluate memory persistence across switch reboots.
The `running-config` resides in volatile RAM. If the switch reboots before `copy running-config startup-config` or `write memory` is executed, any dynamically added sticky MAC lines in RAM are lost.
Determining why sticky MAC entries disappeared after the reboot.
3
Identify the required administrative action to preserve sticky MACs.
Saving the running configuration commits the dynamically learned sticky MAC lines to NVRAM (`startup-config`), ensuring persistence across power cycles.
Pinpointing the missing step causing the loss of network access.

Anahtar Kavram

Port Security Sticky MAC Address Persistence
Tahmini Süre:1m 15s
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Konular

Layer 2 Security Features (Port Security, DHCP Snooping, DAI)

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