Hi Arix,
Please find the answer to your queries below:
1-) For the following constant log message on the 4200ex in vc, there is a https://kb.juniper.net/InfoCenter/index?page=content&id=KB24127&actp=search&viewlocale=en_US&searchi...
Any one has any ideas for investigating the cause?
A) The cause is already mentioned in the KB article which you've linked. If you would like to investigate the cause, then please check the chassisd and messages log for any events related to daemon:deamon, pfed mib2d, craftd license-check etc. If you don't find anything then please reach out to JTAC for further assistance.
2-) Couldn't find any resource about the following chassisd log...Can I ask about what missing this VC as there is no alarm on system and chassis?
fru_is_present: out of range slot 0 for
fpm_get_sys_led: FPM display module missing
fru_is_present: out of range slot 0 for
fpm_get_sys_led: FPM display module missing
A) The syslog which you're seeing is not related to any critical events and that's the reason no alarms were triggered.
3-) The following snmpd log messages are happening all the time...never stop! How to address this issue. And another qs is what reason could be that the vlan l3 interface is engaged to snmp stuff?
A) SNMPD_AUTH_FAILURE means the authentication was failed when polling an interface on the device. From your log, it seems like polling is done from the IP source 10.232.232.20 towards 10.30.85.1 with an incorrect community. If you don't have SNMP configuration then someone is initiating the polling towards your EX. You can check using "monitor traffic interface" command whether you're receiving polling traffic or not and can create a loopback filter to block this traffic.