Cisco switches enter reboot loops due to DNS client bug
⚠️ Multiple Cisco switch models are entering reboot loops after an apparent firmware bug in the internal DNS client began treating DNS lookup failures as fatal errors. The problem began around 2 AM and affected devices log fatal DNS_CLIENT errors (for example 'SRCADDRFAIL' when resolving 'www.cisco.com'), then reboot every few minutes, seriously disrupting network operations. Administrators report affected lines include CBS, SG and Catalyst C1200/C1300 series. Temporary mitigations include disabling DNS or SNTP on management interfaces or blocking outbound management access while Cisco investigates.
