$TTL 1D
@       IN SOA  ns.linux.vm. root.linux.vm. (
                                        2015051501      ; serial
                                        1D      ; refresh
                                        1H      ; retry
                                        1W      ; expire
                                        3H )    ; minimum
        IN      NS      ns.linux.vm.
201     IN      PTR     ns.linux.vm.
202     IN      PTR     L1.linux.vm.