Cisco Business Switches Reboot with Fatal Error from DNSC Process

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Updated:January 8, 2026
Document ID:1767916364268164

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kmgmt3846-cbs-reboot-with-fatal-error-from-dnsc-process

Products Affected

Model

Firmware Version

Bug ID

SG350/SG550

2.4.0.91, 2.4.0.92, 2.4.0.94

CSCvk43809

Catalyst 1200/1300

4.1.7.24

CSCws68844

CBS 250/350

3.5.3.2

CSCws68935

Issue Description

In the Catalyst 1200/1300 switches and CBS 250/350 series switches, the device reboots with fatal error from Domain Name System Client (DNSC) process.

The following is an example log entry of the error:

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Workaround

The issue seems to be due to the switch's inability to handle certain DNS response format and is isolated to few DNS servers. To stabilize the switch, the following workaround (s) are suggested:

  • Try an alternate DNS Server (example: Cisco OpenDNS DNS servers)
  • Remove DNS Name lookup functionality
  • Use static name-to-address mappings:
    1. In CLI, use the "ip host" command
    2. In the web user interface (UI), navigate to General IP Configuration > DNS > Host Mapping
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Revision History

Revision Publish Date Comments
1.0
08-Jan-2026
Initial Release

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