Comment 1 for bug 1940563

I suppose you use Openstack version before Yoga.

Reproduced the bug in Victoria version.
Found error messages in designate mdns log:

2022-05-13 10:33:27.859 11 INFO designate.dnsutils [req-c8db1305-c9be-4f82-9191-0d30792319f4 4d81fe6db2cc473082ff2590e363651f 094a78d8bd52449884839b0c51a97e65 - - -] Doing AXFR for example.ru. from {'zone_id': '12cf8890-252f-4115-ad6c-1f9bc853e2ca', 'host': '100.66.48.209', 'port': 53, 'id': 'ce6c35f4-3293-4e17-82b7-4a06bf1d753d', 'created_at': datetime.datetime(2022, 5, 13, 10, 33, 27), 'updated_at': None, 'version': 1}
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils [req-c8db1305-c9be-4f82-9191-0d30792319f4 4d81fe6db2cc473082ff2590e363651f 094a78d8bd52449884839b0c51a97e65 - - -] Problem doing AXFR example.ru. from {'zone_id': '12cf8890-252f-4115-ad6c-1f9bc853e2ca', 'host': '100.66.48.209', 'port': 53, 'id': 'ce6c35f4-3293-4e17-82b7-4a06bf1d753d', 'created_at': datetime.datetime(2022, 5, 13, 10, 33, 27), 'updated_at': None, 'version': 1}. Trying next server.: TypeError: '>' not supported between instances of 'float' and 'NoneType'
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils Traceback (most recent call last):
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils File "/var/lib/openstack/lib/python3.8/site-packages/designate/dnsutils.py", line 359, in do_axfr
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils raw_zone = dns.zone.from_xfr(xfr, relativize=False)
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils File "/var/lib/openstack/lib/python3.8/site-packages/dns/zone.py", line 1106, in from_xfr
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils for r in xfr:
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils File "/var/lib/openstack/lib/python3.8/site-packages/dns/query.py", line 611, in xfr
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils if mexpiration is None or mexpiration > expiration:
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils TypeError: '>' not supported between instances of 'float' and 'NoneType'
2022-05-13 10:33:27.885 11 ERROR designate.dnsutils
2022-05-13 10:33:27.888 11 WARNING designate.mdns.xfr [req-c8db1305-c9be-4f82-9191-0d30792319f4 4d81fe6db2cc473082ff2590e363651f 094a78d8bd52449884839b0c51a97e65 - - -] XFR failed for example.ru.. No servers in [{'zone_id': '12cf8890-252f-4115-ad6c-1f9bc853e2ca', 'host': '100.66.48.209', 'port': 53, 'id': 'ce6c35f4-3293-4e17-82b7-4a06bf1d753d', 'created_at': datetime.datetime(2022, 5, 13, 10, 33, 27), 'updated_at': None, 'version': 1}] was reached.: designate.exceptions.XFRFailure: XFR failed for example.ru.. No servers in [{'zone_id': '12cf8890-252f-4115-ad6c-1f9bc853e2ca', 'host': '100.66.48.209', 'port': 53, 'id': 'ce6c35f4-3293-4e17-82b7-4a06bf1d753d', 'created_at': datetime.datetime(2022, 5, 13, 10, 33, 27), 'updated_at': None, 'version': 1}] was reached.

This error in dnspython was fixed in version 2:
https://github.com/rthalley/dnspython/commit/9fbf9b223dc26262b1cf23f623f89283ee9c8375

Openstack bumped dnspython to version 2 in Yoga.
Need some workaround for openstack version prior Yoga.