DHCP for Multiple NTP Servers and how to use time offset as an integer

Thygo
New here

DHCP for Multiple NTP Servers and how to use time offset as an integer

If someone has experience in setting the following it would be appreciated.

 

#1 How to set multiple NTP Server's as IP.

I would prefer to use an NTP Time Pool Server list like "au.pool.ntp.org" however the DHCP Server settings only permit using IP addresses and not domain names.

I get that this can add CPU utilisation required for lookup, but still, for a device like these it's a small load impact.

The issue with using IP addresses is there is no redundancy setting that is easily understood or documented on meraki.com

 

Question Can I use a delimiter to add multiple NTP Servers to the DHCP Option 42?

If so what is it? "comma | collon | space"?

or do we need to put in multiple Option 42's for each IP?

 

Question (ENHANCEMENT REQUEST!) What would it take for Meraki to support DHCP Option 42 as a DNS name lookup rather than an IP Address and resolve that for the host automatically before handing out the resolved IP as required?

-- This is probably a wider discussion around all DHCP Server products in the meraki portfolio supporting this, Firewalls, AP's etc

-- This is likely an opportunity here for using a drop down list of country pools if someone was so inclined to codify that.

 

#2 NTP Time Server Offset as an Integer

Can someone provide an example of using the NTP Time Zone Offset as an integer to make sure I've used this correctly.

I'm use to providing these as HEX values on Cisco Routers, so I was not 100% sure that I was using the correct signed integer value.

Based on my past experience using this:

https://www.cisco.com/c/en/us/support/docs/broadband-cable/cable-modem-termination-systems-cmts/1218...

 

In my case I was using UTC +10 as

10 hours x (60 minutes / hour) x (60 seconds / minute) = 36000 seconds.

An setting the integer as 36000

 

I'm going to assume that is correct I've had some issues validating this is working correctly on my hosts

 

- Martin

6 REPLIES 6
Thygo
New here

I just validated you can't add multiple DHCP option 42 settings for NTP Servers to the list
ERROR Message "Multiple DHCP options cannot use the same code"
PhilipDAth
Kind of a big deal

I have never seen anything which uses the DHCP NTP option.  What are you using that uses it?

Mostly Android Tables (wifi only devices) and a bunch of Linux Servers

It's well noted that Apple and Microsoft products do not honour these DHCP options

PhilipDAth
Kind of a big deal

Have you considered setting setting up an NTP multicast server on premise?

MerryAki
Getting noticed

I would like to hang on to this.
Might it be possible to add multiple NTP IP servers or hostname as option 42? Would be great to see something like this within the documentation, or if not implemented yet, in future releases 😉

MerryAki
Getting noticed

Don't mind, i utilized this page(Relevant for DE 🇩🇪😞 NTP-Server (hullen.de)
and entered:

192.53.103.108,192.53.103.104,192.53.103.103

First three ptb servers (official authority for time services and other scientific services in DE)

I did a research on several pages, some mentioned that it should be comma-separated 😉

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