DNS. Is it possible to write several A-records without NS?

Question

Domain Name System

The task is to set up Round Robin.
I want to take 4 hosting accounts, 3 workers and 1 in which to register everything.
Hosting has an ip for the domain (A-record) and a server ip (NS)
After reading about Round Robin, I got a little confused.
If I want to register several ips only for A, do I need to register NS as well? Or will it work anyway?
Example
Host 1
A 1.1.1.1
ns1.host1.ru
ns2.host1.ru
Host 2
A 2.1.1.1
ns1.host2.ru
ns2.host2.ru
Host 3
A 3.1.1.1
ns1.host3.ru
ns2.host3.ru
Host 4
A 4.1.1.1
ns1.host4.ru
ns2.host4.ru
In the fourth account, I will write
A 1.1.1.1
A 2.1.1.1
A 3.1.1.1
A 4.1.1.1
and ns will remain fourth. Will it work? If not, why and how?

Answer 1

There is a domain: example.com.
There are entries in his zone file:

NS ns1.example.com.
NS ns2.example.org.

@ MX 10 mx.example.com.

@    A     10.0.0.10
www  A     10.0.0.10
sub  CNAME other.service.on.another.example.org.
ns1  A     10.0.0.9

In order for browsers to understand where to send requests, they ask DNS servers known to them (system servers, they ask providers, etc.) for information about the example.com domain. NS records are the addresses of servers that will be responsible for all DNS requests to this server.
Those. to find out the IP behind the `example.com` domain, the browser learns that `ns1.example.com` and `ns2.example.org` know everything about it. Ask one of them, they look up the A entry for @ and return `10.0.0.10`.
For any other subdomains (such as `www`, or `sub`, or the same `ns1`) or mail needs (MX-record), everyone will ask exactly the addresses that are registered as NS-servers.
If you have 2 different servers responsible for `example.com`, then you need something like this:

NS ns1.example.com.
NS ns2.example.org.

@ MX 10 mx.example.com.

@    A     10.0.0.10     ;; хостер 1
@    A     192.168.0.10  ;; хостер 2
www  CNAME example.com.
sub  CNAME other.service.on.another.example.org.
ns1  A     10.0.0.9

NS servers will know about two, three, etc. different servers that are responsible for 1 domain. Round robin works on the principle of a "balancer" with a normal distribution: one browser will return `10.0.0.10`, another `192.168.0.10`. After some time, both can give the same results or vice versa.

Answer 2

you just need to create the same records with different ips
, while the dns server itself must support round robin, if it does not support then there will be no round robin