Parsing the work of dns and connecting a subdomain to another ip

Question

Domain Name System

I'm a little confused about DNS records.
Given:
There is a domain. example.com.
There are two servers with ip : 1.2.3.4 and 5.6.7.8
Task:
- example.com should return 1.2.3.4
- images.example.com should return 4.5.6.7
Questions:
a) Can I, using only the example.com domain registrar create A records for the task above? I clarify - do I need to somehow declare on the hosting itself that it should accept a certain domain? If not, then it turns out that I can create a record on the Google server is acceptable and when you go to example.com, the Google page will be visible?
b) I came across a dns hosting from Yandex: pdd.yandex.ru - confirmed the domain and delegated it to the dns server of Yandex, created two A records (for @ (root) and images) - as a result, nothing resolves on the domain. Maybe I don't understand something and Yandex dns hosting is only for mail service? If yes, then the delegation of the domain to Yandex = using it only for mail purposes?
c) What is the usual scenario for linking a domain name and hosting?
A person registers a domain, let's say godaddy. Then he buys hosting, let's say from ... hetzner and transfers the domain to hetzner's ns server by registering them with godaddy? And further already on editing dns of zones hetzner'a adds A record for the server 5.6.7.8?
Help put the puzzle in place in my head.

Answer 1

A) You can add any entries in the domain control panel (where you bought it). Just when adding an A-record, you need to specify the IP address. If you have a dedicated IP on the hosting, then you don’t even have to transfer anything to the hosting NS servers - you can attach this dedicated IP address to the domain both on the left and on the side, as you like. Usually hosting NS servers need to be registered in the case when the hoster does not give you a dedicated IP address. In this case, on their NS, information about the IP address will quickly change, and if you have tied their NS servers to the domain, everything will be updated automatically.
DNS matches Internet addresses and IP addresses. Further, the browser, when it found out from DNS which IP address example.com is located on, knocks on this IP and says: “give me the index.php file from the example.com site”. The web server looks and sees that it has example.com in its settings, pulls out and interprets the index.php file from the corresponding folder. In a situation where Google's IP is registered in the DNS for images.example.com, the browser knocks on Google's IP and asks for some file from images.example.com, and Google answers: the settings are not set to serve requests for the images.example.com site. You can write anything in your DNS, but I have the web server settings and there is nothing about images.example.com there.
)Yes something like that. Buys a domain and in the domain control panel (from godaddy) prescribes NS-records @.example.com indicating Hetzner NS-servers in them. Then at Hetzner it will be possible to add subdomains in the control panel.