Your local entries look fine, at least the IPv4 that I looked at. Nothing really tricky there. Your serial number of the file is a little old (2006), but that should not matter (I use the same format as you do). I did not see the "default-zones" file. I am hoping you are not conflicting the "mtu.net" domain (with this mn.mtu.net named) through that file, but I do not see how that would create issues with resolving outside hosts. Sorry, I am no help.