How to set up DKIM correctly?

Question

Domain Name System

Faced a confusing situation:
The domain is registered with the first hoster (1Gb)
The site is hosted by the second hoster (Spaceweb)
The mail server is rented from the third hoster (Masterhost)
Task: configure DKIM for mail.
1. I activate the service in the Masterhost control panel and get the public key.
2. In the DNS settings of the first hoster (1GB) I make a txt DKIM record with a public key.
3. I test with several services and everywhere they show a DKIM error (DNS Record not found, DKIM-Result: permerror (no key), etc.), and the second one (Speyweb) turns out to be the answering service.
Help, please, to understand. How to properly configure DKIM with this configuration.

Answer 1

nslookup -q=ns
So you will understand which DNS server holds your zone, there will most likely be two of them) And you need to configure the record there.