AXFR record type is useful to get a list of DNS records for a zone:
$ dig -t axfr example.com @192.168.1.1 | head -10 ; <<>> DiG 9.9.5-4-Debian <<>> -t axfr example.com @192.168.1.1 ;; global options: +cmd example.com. 86400 IN SOA ns1.example.com. admin.example.com. 2011100600 3600 1800 604800 3600 example.com. 86400 IN NS ns1.example.com. alice.example.com. 86400 IN A 192.168.1.2 bob.example.com. 86400 IN A 192.168.1.3 bob.example.com. 86400 IN A 192.168.1.4 bob.example.com. 86400 IN AAAA 38a1::3 bob.example.com. 86400 IN AAAA 38a1::4 ...
Not all DNS servers allow zone transfer, because that might not be good from a security perspective.
So AXFR support in Zabbix agent would be useful for monitoring the DNS security setup, as well as zone content, too.