How can I solve authentification problem with kerberos ?

Each machine must have a "principal" in the kerberos database, and a "key" (== a password). The key is saved encrypted on the machine itself in /etc/krb5.keytab (for kerberos5) and /etc/srvtab (for kerberos4). If you change the name of a machine, you must create a new principal, and re-create keytab and srvtab.

To do that, you have a script, or an RPM, or a NCM component, depending on the version of linux and the way the machine has been configured. In any case, the name contains "srvtab" or "keytab". I suggest you look first for cern_config_srvtab in /usr/bin You would have to run it as root, with the -f option to force a refresh of the keytab. Once it is done, you MAY have to wait until the day after until it works (thanks for some caching of the machine's credentials)