Dear Shu. Thanks for that explanation. >> Concerning RH or CentOS: I have to define /etc/hosts on all machines >> that do not obtain their hostname via DHCP. I have not yet figured out >> that the HOSTNAME variable in /etc/sysconfig/network is used in any >> form (correct me if I am wrong). > > See /etc/rc.d/rc.sysinit. In that file you can find following lines > > ---- > (snip) > > if [ -f /etc/sysconfig/network ]; then > . /etc/sysconfig/network > fi > > (snip) > > # Set the hostname. > update_boot_stage RChostname > action $"Setting hostname ${HOSTNAME}: " hostname ${HOSTNAME} > > (snip) > ---- > > The ${HOSTNAME} variable comes form /etc/sysconfig/network. I still wonder why it also works if hostname is only set in /etc/hosts like: 127.0.0.1 localhost 10.0.0.50 myserver.domain.example myserver and $HOSTNAME is undefined. Best Regards Marcus