host principals and fully qualified doamin names - Rlogin options

[fsoliv]

Hello,

Do the principal host for my machines have to have the fully qualified
domain name?

I have kerberized rlogin but whenever I want to tlogin to machine 1 I
have to type machine1.ex.com. Problably I can make dns alias but is
there any other way to prevent my users typing the fully qualified
domain.

Also, I want my users credentials to be forwarded to every new rlogin
session. In order to do theu have to type rlogin -F machinename.ex.com
everytime. Is there any way to tell rlogin to use the -F option by
default?