[cisco-voip] CCX and NTP

[Anthony Holloway]

I'm pretty sure that Cisco IOS only queries DNS under two circumstances:

1) The moment you enter the command.  So you can write some script to
remove the commands and re-add them every so often.

2) The moment the router powers on and reads that section of config into
memory.  So you can reboot your routers every so often.

For UC apps, I have no idea how often it queries DNS to pull a fresh set of
servers from pool.ntp.org.  Never cared, because like Ryan Huff, I don't
point UC apps externally, rather I build a hierarchy of NTP in the
environment.

Speaking of pool.ntp.org, you should really be using the closest servers to
you, which according to ntp.org, means I would use:

0.us.pool.ntp.org
1.us.pool.ntp.org
2.us.pool.ntp.org
3.us.pool.ntp.org
etc.

However, I have seen CUCM fail an upgrade because the NTP config had a name
which started with a number.  So, be careful out there kids, it's a tricky
mine fields to navigate.

On Mon, May 8, 2017 at 9:53 AM Charles Goldsmith <wokka at justfamily.org>
wrote:

> To expand on this, I would point to your voice gateways with everything
> internal, then the voice gateways would either use an on-prem NTP server
> that is radio sync'd or one that Neal has advised.  That way, everything is
> synced together with the same source.
>
> For UCCX and other apps, I point them to the UCM pub and the pub points to
> the voice gateways.
>
> I've seen a lot of people advise for pool.ntp.org, but that has bitten
> me.  How often does an NTP process refresh from DNS?  I suspect only on
> reboot or a restart of the NTP process.  I've seen too many NTP servers go
> offline when using the pool addresses.  Because of that, I've been sticking
> with .gov based NTP on the voice gateway.
>
> Ryan Huff, one thing about pointing to strata 1 servers, most of them have
> restrictions from what I've seen, while they work, they could block you for
> not being approved if you send too many requests.
> http://support.ntp.org/bin/view/Servers/StratumOneTimeServers has a list,
> and while many have open access listed, if you look at the details, they
> can still have restrictions.
>
> Just food for thought.
>
> On Mon, May 8, 2017 at 9:20 AM, Haas, Neal <nhaas at co.fresno.ca.us> wrote:
>
>> Get an on-prem NTP server, if you cant spend the money, use:
>>
>>
>>
>> time.nist.gov     global address for all servers       Multiple locations
>>
>> utcnist.colorado.edu      128.138.140.44  University of Colorado, Boulder
>>
>> utcnist2.colorado.edu    128.138.141.172                University of
>> Colorado, Boulder
>>
>> time-nw.nist.gov             131.107.13.100  Microsoft, Redmond,
>> Washington
>>
>>
>>
>> Really, anything with a GOV, or EDU should be good.
>>
>>
>>
>> By the way, you should NEVER, EVER, EVER (can’t stress this enough) a
>> Windows Based NTP.  Every place that I have went into and removed a Windows
>> Time server, everything has worked better! Windows just cant do time. I
>> went into a business with windows NTP, and the guy was checking time from
>> about 100 NTP servers, his time was off by three minutes. Took it down to 3
>> and everything started to work.
>>
>>
>>
>> Thank You,
>>
>>
>>
>> Neal Haas
>>
>>
>>
>> *From:* cisco-voip [mailto:cisco-voip-bounces at puck.nether.net] *On
>> Behalf Of *Ben Amick
>> *Sent:* Monday, May 8, 2017 7:12 AM
>> *To:* cisco-voip at puck.nether.net
>> *Subject:* [cisco-voip] CCX and NTP
>>
>>
>>
>> What do you guys use for NTP on your CCX hosts? I’ve been informed by TAC
>> that “CCX does not support Windows based NTP” so I was thinking about just
>> pointing NTP towards my CCM hosts – is that a valid scenario? I figure that
>> since CCM is pretty much authoritative on everything for CCX as it is it
>> wouldn’t be a problem?
>>
>>
>>
>> *Ben Amick*
>>
>> Telecom Analyst
>>
>>
>>
>>
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