Who gave Yandex NS?

Question

Domain Name System

Yandex services are not working stably this weekend. Many complain about the unavailability of VK, disk and other things.
downdetector.ru/ne-rabotaet/yandex
Yandex itself, in fact, pushes back "everything works for us, shake your providers."
On Monday, the corporate segment began to stir :-)
Let's start to understand - crap with DNS. Some "Smart pieces of iron" made dns trap on many third-level names *.yandex.ru
What's wrong with DNS?
We look:

по данным WHOIS.NIC.RU:
domain:       YANDEX.RU
nserver:      ns1.yandex.ru.
nserver:      ns2.yandex.ru.
nserver:      ns9.z5h64q92x9.net
state:        REGISTERED, DELEGATED
admin-contact:https://www.nic.ru/cgi/whois_webmail.cgi?domain=YANDEX.RU
org:          YANDEX, LLC.
registrar:    RU-CENTER-RU
created:      1997.09.23
paid-till:    2017.10.01
source:       RU-CENTER

>>> Last update of WHOIS database: 2017.06.05T12:19:13Z <<<

What is this ns9.z5h64q92x9.net appeared SUDDENLY

according to history

ПРОМЕЖУТОК ВРЕМЕНИ
ДАННЫЕ WHOIS ЗА ЭТОТ ПРОМЕЖУТОК ВРЕМЕНИ

с 2014.10.01 по настоящее время

<code>domain:        YANDEX.RU
nserver:       ns1.yandex.ru. 213.180.193.1, 2a02:6b8::1
nserver:       ns2.yandex.ru. 93.158.134.1, 2a02:6b8:0:1::1
state:         REGISTERED, DELEGATED, VERIFIED
org:           YANDEX, LLC.
registrar:     RU-CENTER-RU
created:       1997.09.23
paid-till:     2015.10.01
free-date:     2015.11.01</code>

с 2013.10.30 по 2014.09.30

domain:        YANDEX.RU
nserver:       ns1.yandex.ru. 213.180.193.1, 2a02:6b8::1
nserver:       ns2.yandex.ru. 93.158.134.1, 2a02:6b8:0:1::1
state:         REGISTERED, DELEGATED, VERIFIED
org:           YANDEX, LLC.
registrar:     RU-CENTER-REG-RIPN
created:       1997.09.23
paid-till:     2014.10.01
free-date:     2014.11.01

At first glance, it belongs to Yandex and leads to Finland.
What is it? Yandex is having fun or MiTM?

Answer 1

https://geektimes.ru/post/289801/

Answer 2

It is normal practice to spread DNS servers over different networks, in case of loss of network connectivity, the address will still be resolved. And network connectivity can be lost not only due to technical failures, but also due to events in Ukraine, for example. The fact that the address is placed in a separate domain allows you to quickly change it without waiting for the .ru zone to be updated, which occurs only a few times a day.