how to override dhcp hostname.

[william Famy]

Hello

I am looking how to override the hostname sending by dhcp.

I am looking how to create a menu (like grub) wich allow me to choose 
the class during boot sequence

Ex I want to update a computer and i want to choose my class just after 
pxe.0

Is it possible to modify the pxelinux.cfg/default to choose class? I try 
to append hostname but nothing.

Is there any idea?

thanks for any help.  regards