Why hasn't the IP of the subdomain changed to biz.mail.ru?

Question

Domain Name System

Hello colleagues!
Faced with a situation that makes the brain clean.
In our company, the external IP address has changed, or rather its last 2 digits, from 22 to 15. After that, I made changes to the domain control panel for all subdomains. However, on one of the subdomains on which we have the Bitrix24 portal, the IP value has not changed. I contacted biz.mail.ru support with the request below:

Here are the entries:
And here is the DNS 8.8.8.8 response:
The same response from 2ip.ru:
All subdomains except b.olmio.com changed their ip, but this one didn't. How is this possible, perhaps a failure?
Look, for example, the ex.olmio.com subdomain:
The same answer from 2ip.ru:
Correct, please!

Here is what they answered me:

Please contact your hosting provider regarding this matter.

What does the hosting provider have to do with it (we generally have our own servers), if all DNS servers resolve the b.olmio.com domain name to the old ip address?

Answer 1

Judging by the data of nslookup - the server of the domain b.olmio.com
troitsk.ens.mail.ru
miass.ens.mail.ru
And these records lead to the 22nd
SP, while the kovrov.ens.mail servers are indicated for the olmio.com
domain. ru
sarov.ens.mail.ru
There, b.olmio.com also resolves as 95.161.11.22
So in this case, kick mail.ru support - they have your DNS zone, let them deal with non-use.