DNS for three local domains - how?

Question

linux

For the first time in a long time, even Google did not help!

Introductory: there is a VPS with Ubuntu 20.04. It hosted Zabbix and OpenVPN servers. Three routers from different offices connect to the latter. Routing is configured, everything behind the routers is pinged and available for VPS. These are office computers, printers, cameras, etc.

Zabbix should monitor all these hosts by banal ping.

But I really want Zabbix to add all this to itself not by IP addresses, but by domain names, since each of the routers has a DNS server from where you can get these names.

And the whole gag is that it is impossible to configure so that the VPS can do nslookup of all three subnets at the same time! With one easily, but immediately in three ...

I came closest to the solution using dnsmasq, with entries in its config like this:

server=/msk/192.168.0.1
server=/spb/192.168.10.1
server=/ekb/192.168.88.1

With them, for example, the printer1.ekb domain successfully resolves to 192.168.88.100 at the router 192.168.88.1, but it doesn’t work the other way around!

[email protected]:~# nslookup 192.168.88.100
** server can't find 100.88.168.192.in-addr.arpa: NXDOMAIN

Answer 1

configure slave dns on VPS transfer zones from masters or master.
and reverse zones as well

Answer 2

If you have all this within a single infrastructure, then it is not clear why there are so many DNS servers. Modern routers are quite capable of either forwarding requests or even becoming slave servers. And since there is only one source, there will be no problems like "it resolves here, it doesn't resolve here."

Answer 3

Do you have PTR zones configured? This is a separate entity.
If yes, you need to send requests for PTR records via dnsmasq in the same way