This is something which you may need to check while troubleshooting a network card related issue on ESXi host and want to cross verify the vmnic driver / Firmware version compatibility with VMware HCL.
In order the check the required vmnic driver/firmware detail, first connect the to the desired ESXi host over ssh using Putty or you may also connect to DCUI,
Now use following command to get detail of connected network cards,
There is also a legacy command to get the same information,
# esxcfg-nics -l
# ethtool -i vmnic_name
Or
Or
# esxcli network nic get -n vmnic_name
That's it... :)