DNS setting up an incoming A record -- Part 2

Hello, further to This topic here,
I've clarified a few things:

- Client's DNS (not on our servers) now shows:

HOST - TTL - TYPE -  DATA
domank.net.  -  3600  - A  -  123.345.567.789 (our server IP)
www.domaink.net.  - 3600 -    CNAME  -  domaink.net

Our server has NO DNS ENTRY at all for the clients domain.

- We have set up a WHM "Configure Remote Service IPs" which shows the "Remote Name Server IPs"

(only) as their DNS location as found from running

nslookup -type=soa domaink.net

 

Which returns a Google IP address where their DNS is set.

So, I believe that once this is set up on the account on our server we can then use
"Domain Alias" on the CPanel account to accept delegation to/from their DNS for this address (domaink.net).

BUT:

Adding an alias comes back with this error :

There was an error when the system attempted to create the alias. (XID k47rad) This domain points to an IP address that does not use the DNS servers associated with this server. Transfer the domain to this server’s nameservers at the domain’s registrar or update your system to recognize the current DNS servers. To do this, use WHM’s Configure Remote Service IPs interface.

1) IS this the correct way of setting up a 3rd party A record to point to an account on our server?

2) Do we just need to wait for longer for the DNS to update? It's been an hour or so (more than their DNS TTL) ?

3) How can we resolve this issue?

Thanks .

NOTE: because the forum is broken I am unable to leave replies (no submit button on HTML on any browser). So am adding this development / update info as a part 2. I will update this Q with edits as per if any replies here need it. Thanks.

 

UPDATE 1

Thanks Rex,
There is an issue; that I have created a DNS record on our server with the NS / SOA / A records and the website (domaink.net) does reach our server, and is associated with the correct account on the DNS set up steps.

- But, I can't seem to retain the A record without also retaining the NS records and SOA records (no idea if these need to be removed?)

- Browser fails to load the pages of the account. Instead stating the cgi-sys/defaultwebpage.cgi default fail page. Depite the domain being associated with the account.

- In the CPanel account I can't set any Domain additions (alias / domain / etc. ) because one already exists. That's to be expected, but then if I delete the WHM DNS records mentioned above (NS / SOA / A / etc.) and restart the DNS service, the CPanel Domain tools all fail with variations of the error:

There was an error when the system attempted to create the alias. (XID uvyvm4) This domain points to an IP address that does not use the DNS servers associated with this server. Transfer the domain to this server’s nameservers at the domain’s registrar or update your system to recognize the current DNS servers. To do this, use WHM’s Configure Remote Service IPs interface.   

Which as mentioned before we have the DNS IP in our  "WHM’s Configure Remote Service IPs" but it seems not to recognise the remote DNS delegating A records only? This means we in effect can't use the CPanel level domain tools to set up.

Would you be able to give some steps how to associate the incoming DNS A record (which as said, does now reach our server) with an account on the Account List (the account already has another primary domain, I don't want to change the primary domain).
For ease let's assume all DNS records on our server are blank and start from scratch.

Thank you :)