Daylight saving time

As explained in Acing the CCNA Exam: Volume 2 Advanced Networking and Security

Daylight saving time is a seasonal clock adjustment that advances local time in spring and reverses the adjustment in fall.

Daylight saving time (DST), also called summer time, advances clocks in spring and reverses the adjustment in fall. Network devices in regions that observe DST should adjust their clocks accordingly. section 2.1.2

Configure the seasonal adjustment separately from the device’s time-zone offset:

• Enter global configuration mode and use clock summer-time name recurring start-date-time end-date-time. section 2.1.2
• Specify the daylight-saving name, recurring schedule, starting date and time, and ending date and time. section 2.1.2
• For Toronto, the schedule begins at 02:00 on the second Sunday of March and ends at 02:00 on the first Sunday of November. section 2.1.2

Figure 2.1 The syntax of the clock summer-time command. The example specifies that EDT begins at 02:00 on the second Sunday of March and ends at 02:00 on the first Sunday of November.

Inspect the annotated syntax example for configuring a recurring DST schedule. section 2.1.2

How Acing the CCNA Exam: Volume 2 Advanced Networking and Security covers it

How deep it goes

Defines the seasonal behavior and configuration command, but stops short of verification output or troubleshooting procedure.

Examples

Uses Toronto’s recurring schedule: 02:00 on the second Sunday of March through 02:00 on the first Sunday of November.

What it assumes

Assumes a configured or understood time-zone offset and a known regional daylight-saving schedule.

What you can do after

Configure recurring daylight-saving changes on a Cisco IOS device.

How it connects

Connects daylight saving time with time zones, UTC offsets, software clocks, and Network Time Protocol.

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Related concepts

• clock summer-timeconfigured by · clock summer-time is a Cisco IOS global configuration command that defines recurring daylight-saving-time transitions.
• timestampcontrasts with · A timestamp is a value representing a specific point in time, typically associated with an event, observation, or data item.
• timeused by · TIME is a temporal data type representing a time of day without calendar-date information, optionally with fractional-second precision.
• time zoneaddressed by · A time zone is a geographic or rule-defined region whose local civil time is determined by offsets and calendar-time rules relative to a reference time standard.

This explainer was generated by Manning's knowledge graph from the text of Acing the CCNA Exam: Volume 2 Advanced Networking and Security. The section links point to the parts of the book it draws on.