Answered Question
Sep 24th, 2009


Please can some one help me with this?

I configured a time based access control list for our internet router to allow certain users access at different time and it is working ok. But my problem is that our network for now is not an always on network so each morning when we had to start the day, i have to manually set the clock time and date of the internet router to the current time so that the ACL can work properly.

Is there any way the time setting can be automated so that once started for the day, the time and date will synchronise with the current server time and date.

Thanks for your help.


Correct Answer by Leo Laohoo about 7 years 5 months ago

How to configure an authoritative time server in Windows Server

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Overall Rating: 5 (1 ratings)
John Blakley Thu, 09/24/2009 - 10:23


Depending on the version of IOS, you should just be able to do:

ntp server

or if the above doesn't work, use:

sntp server

You'll need to sync to a time server like, or you'll need to configure your server as a stratum time server on Windows (not sure how to do that, but there's documentation on it.)



tprendergast Thu, 09/24/2009 - 10:51

Hi Tom,

You can use kron for this, relatively simply (unless you wish to use the previous solution of setting an ntp server on both router and host).

Here's a link to 12.3's documentation for kron/command scheduler:

Basic example:

- enable

- config terminal

- kron policy-list mycronjob

- cli clock set hh:mm:ss (example: cli clock set 01:23:45)

- exit

- enable

- conf t

- kron occurrence occurrence-name [user user] {in [[numdays:]numhours:]nummin | at hours:min [[month] day-of-month] [day-of-week]} {oneshot | recurring} (example: kron occurrence dothisdaily at 00:05 recurring)

- policy-list mycronjob

- exit

This will configure the kron to manually set the clock to a certain time. This is valid if you use a software clock and no ntp/etc. If your router uses NTP or has a hardware clock, then perhaps you can just use kron to enable/disable access lists or other methods of enabling/disabling access for users.

Verify it is setup right by doing:

show kron schedule

Hope that helps. Rate if you find this useful!



Lucien Avramov Thu, 09/24/2009 - 18:00

kron is not needed for NTP.

Once ntp is configured, it continuously synchronize the clock of the router and there is no more need to set it manually.

I recommend that you use NTP and synchronize your router.

Then you're router will always be synced and your time ACL wont be an issue anymore.

Joseph W. Doherty Thu, 09/24/2009 - 11:25

You might check if your router has an onboard calendar clock (e.g. show clock). If it does, set it, and router will have correct time when it restarts. Also, if possible, use something like NTP to insure this clock always has correct time.

tomocisco Thu, 09/24/2009 - 23:26


Thanks so much.

I accessed the link you refered me to, on how to configure authoritative time server. It's very imformative and helpful.

How can I get my routers to sync with the time server when configured.



Leo Laohoo Mon, 09/28/2009 - 14:41

Hi Tom,

Thanks for the rating.

As with John's post, this depends on your router. If your router supports only SNTP, then the most simplest command is sntp server . If your router supports NTP then its ntp server . If your router supports both, I'd recommend that you use NTP.

Hope this helps.


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