Hi Prashant,

I think you may struggle in the interview if you need to know this for a job, but I'll help you out provide some guidance for you and anyone that stumbles across this thread in the future.

I HIGHLY recommend you read Chapter 6 (page 39-60) in the following PDF: http://www.vmware.com/pdf/vsphere4/r40/vsp_40_esx_vc_installation_guide.pdf

1) Create a script to provide the configuration options to the installer. EG: there is a default ks-first.cfg provided in the above PDF

2) Copy that ks.cfg file to a location that the 60 hosts can see. This could be a CD or USB media that you put in each server, or it could be a file on a network location (FTP, HTTP, NFS etc).

3) Run the installer on each host (either PXE boot or local media (CD/DVD) install) and use the "Scripted Install" option and point it to your .KS script file.

4) The installation will now take place un-attended on each host. The installation shouldn't take much time to complete unless installing over a slow network link. They can all be installing simultaneously, so provided you have the script and ESX installation media in an accessible location to all hosts, it shouldn't take longer than what 1 installation would normally take (bandwidth limitations aside).

Cheers,