$ORIGIN thing.               ; root domain
@    IN NS   ns.thing.       ; who is responcible for root domain
ns   IN A    11.22.33.44     ; It's me itself so I have to add the "glue record"

$ORIGIN any.thing.           ; subdomain
@    IN NS   ns.any.thing.   ; who is responsible for subdomain
ns   IN A    22.33.44.55     ; address of the ns.any.thing

$ORIGIN some.thing.          ; subdomain
@    IN NS   ns.some.thing.  ; who is responsible for subdomain
ns   IN A    33.44.55.66     ; address of the ns.some.thing