Why is there a delay when changing reverse DNS?

[Alexis]

If the reverse DNS request (rDNS) is changed, there may be a delay. It must be remembered that usually DNS records change over 24, or even 72 hours. There is also the fact that it takes time to update the DNS cache. For example, you changed the rDNS record, having made a mistake and after that you want to change it right away, be prepared for the fact that the cache has already accepted your changes, and it takes time for it to change again.

[Vicento Mine]

I changed the rDNS record, it took 7 hours, sometimes it happens faster

[Steve Baker]

What ns records are needed to register the DNS host service?

[Alexis]

In order to register DNS records in Hostry, you need to register:

ns1.hostry.com
ns2.hostry.com
ns3.hostry.com
ns4.hostry.com

You can register DNS by clicking on the link:

https://hostry.com/products/dns/