We have domains registered with different registrars, all of which use the DNS servers from our rented DNS hosting service. Each domain's necessary DNS zone records are entered there. To add a subdomain, we simply add a corresponding entry A to the zone.

When adding a domain to the hosting service, however, we're once again required to specify DNS servers. Typically, the hosting service's own DNS is already specified by default. But considering there's already an A-type record for the IP server in the DNS zone, is there really a need for this step?

There are some hosting providers that allow for automatic domain linking without any extra steps. This feature is usually only available if you purchased the domain through the same host. If not, certain settings will still need to be configured manually.

Typically, there are two ways to link a domain and hosting:

- When purchasing hosting services, you can register a domain at the same time. This will automatically attach the domain to your hosting account.
- In the hosting control panel, you can find an option to "Bind domain" or "Connect domain". If you registered your domain with the same provider, it will automatically bind. Otherwise, you can still connect your domain, but you'll need to change the NS servers or IP addresses of the NS servers.

If automatic binding is not available, then you'll need to link your domain and hosting manually. There are two ways to do this:

- Change the NS servers in your domain settings. This is the preferred method as changing the IP address of your hosting will automatically reconfigure everything.
- Change the IP address in the DNS records of your domain to match the IP address of your hosting. This method is less favorable because you'll need to repeat the process every time your hosting IP changes and you may also run into issues with site availability.

When linking your domain and hosting, it's important to choose the method that is most convenient for you and your website's needs.

To ensure the smooth operation of your website, it is important that you specify the DNS of your hosting provider. This will inform the domain's DNS server that your sites are located on the host's server, which only the hosting provider can know for certain.

It is worth noting that the host's sites may migrate from one server to another without your knowledge; however, the hosting provider will make the necessary changes on its DNS server to ensure seamless operation of your web site.

DNS is a critical component of website hosting, as it connects your domain name to your web server's IP address. By specifying your hosting provider's DNS, you can ensure that your website runs smoothly and remains accessible to visitors.

A domain name may have multiple resources attached to it, such as a website and a mail server, each with unique IP addresses. This can enhance the dependability and efficiency of the system. Additionally, different subdomains and sites may have unique IP addresses as well.

A DNS server stores all information related to website connection, including subdomains and mail systems, in a specialized file known as a DNS zone. The file contains records like A, which represents a website's specific domain name address, and MX, which is the mail server's address. CNAME is commonly used to link subdomains. NS is another type of record that indicates the DNS server responsible for other resource records. Furthermore, TXT provides textual information about the domain, and SPF specifies the list of trusted servers for emails on behalf of the specified domain. SOA is the initial record that contains essential information about the server and template data regarding the domain name.

When you add a domain to your hosting service, you are essentially telling the hosting provider that you want to associate that domain with a specific server. This step is crucial because it allows the hosting provider to route traffic to the correct server when someone accesses your domain.
Now, when you mention that the hosting service's own DNS is already specified by default, it means that the hosting provider's DNS servers are responsible for resolving the domain names to IP addresses. This is a standard setup, and it ensures that your domain resolves correctly when someone types it into a web browser.

However, the A-type record you mentioned in the DNS zone is specifically related to mapping a subdomain to an IP address. While this is essential for directing traffic to the correct destination within your domain, it doesn't replace the need to specify the hosting provider's DNS servers when adding a domain to the hosting service.

In essence, the A-type record within the DNS zone handles the routing of subdomains, while the specification of the hosting provider's DNS servers ensures that the main domain itself resolves correctly to the designated server.

So, there is indeed a need for this step because it serves a different purpose than the A-type record in the DNS zone. Both steps work together to ensure that your domain functions optimally and resolves correctly for users accessing it on the internet.
While it may seem redundant to specify DNS servers when there are already A-type records in the DNS zone, it's a necessary part of the overall domain management process to ensure proper routing and resolution of both the main domain and its subdomains.

You've got your A record dialed in with the IP in the zone, so why the heck are you forced to re-enter DNS servers when adding a domain to the hosting service? It's straight-up nonsense, a lazy UX fail by the provider. They should auto-sync the nameservers (NS records) from the existing setup instead of making you jump through hoops.

This redundant step is just begging for a fat-finger error or a config mess, wasting your time on basic DNS housekeeping.