example.com.	3600	IN	SOA	ns1.example.com. admin.example.com. 1234 3600 1800 2419200 7200
example.com.	3600	IN	NS	ns1.example.com.
example.com.	3600	IN	NS	ns2.example.com.
example.com.	3600	IN	MX	10 mail.example.com.
www.example.com.	3600	IN	A	192.0.2.1
ns1.example.com.	3600	IN	A	192.0.2.3
ns2.example.com.	3600	IN	A	192.0.2.4

;; DNAME + NS (non-apex) throws ZoneDataUpdater::AddError
ns1.example.com.        3600    IN DNAME    foo.example.com.
ns1.example.com.        3600    IN NS       bar.example.com.