You can check the snmp status using "esxcli system snmp get".
To enable snmp use the following command :
"esxcli system snmp set -e true"
Other parameters can be configured with the following options :
/var/log # esxcli system snmp set --help
Usage: esxcli system snmp set [cmd options]
Description:
set This command allows the user to set up ESX SNMP agent.
Cmd options:
-a|--authentication=<str>
Set default authentication protocol. Values: none, MD5, SHA1
-c|--communities=<str>
Set up to ten communities each no more than 64 characters. Format is: community1[,community2,...] (this overwrites previous
settings)
-e|--enable Start or stop SNMP service. Values: [yes|no, true|false, 0|1]
-E|--engineid=<str> Set SNMPv3 engine id. Must be at least 5 to 32 hexadecimal characters. 0x is stripped if found as well as colons (:)
-y|--hwsrc=<str> Where to source hardware events from IPMI sensors or CIM Indications. One of: indications|sensors
-l|--loglevel=<str> System Agent syslog logging level: debug|info|warning|error
-n|--notraps=<str> Comma separated Usage: esxcli system snmp set [cmd options]
Please let me know if it helps.