In tab Hostname and DNS Client, add a feature to persist DNS settings on reboot.
A check box with text similar to: Persist DNS Servers on Reboot
Then using SED or something, search rc.local (for CentOS) for persist line below and add or replace it:
echo -e "nameserver $DNS_1\nnameserver $DNS_2\nnameserver $DNS_3\nnameserver $DNS_4" > /etc/resolv.conf
Where $DNS_1 - 4 are the the actual variables for the DNS settings on this page, a check to see if 127.0.0.1 is one of them is required.
On a lot of hosted VPS accounts, this can be a pain to resolve for some users, this option should work on any server that uses /etc/resolv.conf, and can be modified to work for systems with other ways to accomplish same task, so care needs to be taken for each supported OS, to deal with OS dependent issues.
There are other ways to accomplish this, but I have found this method works and will not break anything, its only run on boot, so it has little impact on startup time, and will not hurt systems that do not require this, meaning that the server does not overwrite this file on reboot, as is the case with a lot of hosting companies, and placing it in rc.local ensures it gets ran after the server starts up, so the system can overwrite the file before this command runs, preventing it from being stepped on.
This is one major requirement for being able to use this panel on hosted VPS accounts like myhosting.com which uses Virtuozzo, so when it fails System Settings -> Re-Check Configuration, which is every time you install it, the user will see the option to persist setting on reboot, this saves countless questions on how to fix this issue, and its always an issue if you use Virtuozzo, you can also add a note to explain why you want to do this, as well as give you a place to undo it if you are not using the DNS server.
Unchecking it should remove this line if it exist.
Also note that you do not want to write protect this file on Virtuozzo systems, it will lock the VPS up, and you can not even ssh in to fix it, making it far better idea to add a feature to correctly fix this issue for each OS and system type, rather then having the user try to fix it, making this not only a feature request, but a required feature.