This article provides information about the facilities used for ESXi syslog transfer.
VMware vSphere ESXi
When ESXi forwards logs to a remote syslog server, it uses the following facilities:
local6: Used for the VMkernel log (vmkernel.log).
local4: Used for primary ESXi management service logs (e.g., hostd.log, vpxa.log, fdm.log).
Note: Standard syslog facilities, such as kern and user, are also utilized by other ESXi services.