10-30-2008 03:49 PM - edited 03-04-2019 12:08 AM
Hello folks -
I have a question about the upcoming Daylight Savings time change this weekend.
If I configure my routers to synchronize time using an external NTP Server, do I still need the following command configured:
clock summer-time CST recurring 2 Sun Mar 2:00 1 Sun Nov 2:00
I know I still need the following:
clock timezone CST -6
Also, I read somewhere that Cisco routers loose time and date information when rebooted? Is that correct?
Thanks for your help!!
10-30-2008 04:23 PM
re: "Also, I read somewhere that Cisco routers loose time and date information when rebooted? Is that correct?"
Some do, the more powerful models and many of the newer models have on-board clocks. However, the on-board clocks can have inaccurate time, but you can have NTP update them too. (Command is something like "ntp update-calandar")
10-30-2008 04:36 PM
What do you mean by "on-board clocks have inaccurate time?"
What if you set the time manually?
10-30-2008 04:53 PM
Setting either clock manually is fine, but they often "drift". (I.e. gain or lose time each day. One reason for NTP.)
PS:
Also note, the on-board clock I have in mind is the calendar clock, not the since bootup running clock. Again, the former isn't available on all Cisco devices. (Commands, I recall, to see each are "show clock" vs. "show calendar".)
10-30-2008 05:04 PM
Thanks for your reply.
Do you know why do the clocks drift if set manually?
10-30-2008 05:27 PM
Manual setting doesn't have any thing to do with clock drift, they drift normally (something like NTP keeps reseting them).
As to why, this short Wiki article tries to explain: http://en.wikipedia.org/wiki/Clock_drift
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