All Cisco IOS devices support Network Time Protocol (NTP) or Simple Network Time Protocol (SNTP) to learn the time from the network, and some Cisco IOS devices have built-in battery-backed clocks to maintain that time. The clock save interval command is for those Cisco IOS devices that do not have battery-backed clocks and need to know the time and date before they can start communicating with a network. Because the March 1 system default date will likely occur before the valid date of any recently issued certificate, communications attempted with almost any certificate will fail because it is not yet valid according to the local clock.

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