Correct me if I'm wrong, but pre-authentication is a mechanism whereby the KDC requires the client to validate who they are before they are passed a ticket. (https://social.technet.microsoft.com/wiki/contents/articles/23559.kerberos-pre-authentication-why-it... )
The Web Gateway never talks to the KDC, only the client does. As such, I dont think the question is relevant to the Web Gateway, unless the MWG is acting as a client in some way.
Could you provide more context, perhaps I'm mistaken in someway.
Thanks for your fast response! You are absolutely correct.
The pre-authentication setting is not relevant to the Web Gateway. I double checked the Kerberos pre-authentication setting at another customer side who use Kerberos authentication with the Web Gateway and it is enabled by default in the Group Policy. The authentication is working perfectly of course.