Every time the server is restarted the bnconfig tool reconfigures the hostname, as the dynamic IP address often changes when the machine is rebooted. You need to disable the tool by renaming it, to prevent this from happening.
First run it to set the hostname to your domain:
sudo ./bnconfig --machine_hostname your.domain.com
And then rename it:
sudo mv bnconfig bnconfig.disabled
Hope it helps.
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