Check your esxi is physical server or a virtual machine

 ESXCLI command can be used for verifying login (by ssh) esxi server is physical or virtual using:

esxcli hardware platform get

1)Physical:

[root@ranjith-s1:~] esxcli hardware platform get

Platform Information

   UUID: f 0x46 0xbb 0x77 0x4e 

   Product Name: PRIMERGY RX2530 

   Vendor Name: FUJITSU

   Serial Number: XYZABC

   IPMI Supported: true

[root@mva-rx2530-s1:~]

2)Virtual Machine

[root@ranjith-2:~] esxcli hardware platform get

Platform Information

   UUID: 2 0xbd 0x1c 0xa0 0xd4 0x5e 0x32 0x7 0

   Product Name: VMware7,1

   Vendor Name: VMware, Inc.

   Serial Number: VMware-12 34 56

   Enclosure Serial Number: None

   BIOS Asset Tag: No Asset Tag

   IPMI Supported: false