Some customer can take a consult related to time zone configuration when Day light saving time change is required, for example on Chile. Some customer could be expecting to use a specific command to configure and activating the day time zone, hour change in specific moment.

Customer could expect to use this CLI configuration in an attempt to change the time zone when Daylight Saving time is needed:

set system time-zone CLT4SCLT,9.1.0/0,M4.1.0/0.

On MX10003 this command is accepted, however router with NTP configured will be change the time zone to UTC.

UTC is the default time zone configuration on Juniper devices, so, after command is committed then rebooted the router, the time zone will be configured as UTC

set system time-zone CLT4SCLT,10.31.0/0,M4.1.0/0 

commit 

run show system uptime 

Current time: 2024-10-31 01:38:00 UTC

Time Source: NTP CLOCK 

At this point no documentation related to this knob, however the router accepted this configuration and commit it, but no expected effect got it for this command

The recommendation to automatize the time zone and subsequent changes, is to configure the NTP protocol over the network devices

The Network Time Protocol (NTP) provides the mechanism to synchronize time and coordinate time distribution in a large, diverse network. NTP uses a returnable-time design in which a distributed subnet of time servers operating in a self-organizing, hierarchical primary-secondary configuration synchronizes local clocks within the subnet and to national time standards by means of wire or radio. The servers also can redistribute reference time using local routing algorithms and time daemons