The RDATA for an NXT RR consists simply of a domain name followed by a bit map.
The type number for the NXT RR is 30.
1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 3 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| next domain name /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| type bit map /
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The NXT RR type bit map is one bit per RR type present for the owner name similar to the WKS socket bit map. The first bit represents RR type zero (an illegal type which should not be present.) A one bit indicates that at least one RR of that type is present for the owner name. A zero indicates that no such RR is present. All bits not specified because they are beyond the end of the bit map are assumed to be zero. Note that bit 30, for NXT, will always be on so the minimum bit map length is actually four octets. The NXT bit map should be printed as a list of RR type mnemonics or decimal numbers similar to the WKS RR.
The domain name may be compressed with standard DNS name compression when being transmitted over the network. The size of the bit map can be inferred from the RDLENGTH and the length of the next domain name.