General :: Make A File Read-only Even For Root?

Remember back in the days of MS-DOS, a file could have 4 different attributes: archive, read-only, hidden, system. As you know, MS-DOS didn't have any user rights or privileges. Files had no owner. If you were at the command line, you could do whatever you wanted, you could change or delete any files you wanted to... so long as they weren't read-only. Under MS-DOS, if you had a read-only file and tried to delete it, you would get an error saying "Cannot delete read-only file". There was a simple remedy to this, just turn off the read-onlyness:

Code:

attrib -r hello.txt

The point I'm trying to make here is that even though you had full permissions over the file, you still had to turn off its read-onlyness before you could make a change. Well I'm trying to do something similar in Linux. Under Linux, the root user has full permissions over every file. But I need to make a particular file read-only so that not even the root user can alter it. I have a few programs on my computer that need to be run as root because they do some low-level networking (raw sockets and the like), and these programs alter my "/etc/resolv.conf" file. Well I need to find a way of making my "/etc/resolv.conf" file READ-ONLY, even for the root user. It doesn't seem as though the Linux filesystem provides a means of doing this, reason being that the root user will always be able to alter any file it wants to. I was thinking though... there's some way I could turn my "/etc/resolv.conf" file into a virtual file of some sort, like maybe I could use some sort of mount program to mount the file as read-only... ?