kdc.conf

[Ivan]

> Where is your kdc.conf file, and can you verify that krb5kdc is reading
> it?  The default location of kdc.conf is in the KDC data directory
> (typically /var/krb5kdc), and you can explicitly set it with the
> KRB5_KDC_PROFILE environment variable.

Thank you for your reply and your time spent.
The idea turned out to be correct: in the Linux distribution I used, the 
kdc daemon read the /etc/krb5.conf file (and not /etc/kdc.conf). Now 
everything works as it should.
Many thanks again.