I’m attempting to use a 172.16.x.x address in one of my A records. I understand that this isn’t able to be publicly routed, but for my use case, it doesn’t need to be.
My use case:
I have a device that I plug into a computer via the Ethernet port, and it has its own DHCP. The DHCP assigns an IP address to that whichever Ethernet interface I plugged it into, and I can then connect to the device’s web interface via the IP address of the device (ex. 172.16.0.1). The device does not have another connection out, and does not have DNS. I am running dnsmasq on it for DHCP routing, with the following settings:
dhcp-range=172.16.0.2,172.16.0.14,1h
dhcp-option=3
dhcp-option=6
I run a DHCP server on it so that I don’t need to worry about hard-coding a static IP address, configuring the local Ethernet interface to be on the same subnet, etc. This way, I can just plug it in, it’ll assign an address, and just work.
What I’m trying to do:
I would like to use a DNS name to connect to the device instead. That way I can use an address like mydevice.mydomain.com to connect. However, when I put an A record into my DNS for the device, it doesn’t seem to resolve.
This is what my DNS looks like in Cloudflare:
| Type | Name | Content | Proxy status | TTL | Actions |
| ---- | -------- | ---------- | ---------------------- | ---- | ------- |
| A | mydevice | 172.16.0.1 | DNS only - reserved IP | Auto | Edit |
And when I dig the name, this is what I get:
$ dig mydevice.mydomain.com
; <<>> DiG 9.18.1-1ubuntu1.1-Ubuntu <<>> mydevice.mydomain.com
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 1044
;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 1
;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 65494
;; QUESTION SECTION:
;mydevice.mydomain.com. IN A
;; Query time: 76 msec
;; SERVER: 127.0.0.53#53(127.0.0.53) (UDP)
;; WHEN: Fri Jun 17 13:22:18 MDT 2022
;; MSG SIZE rcvd: 41
As you can see, it doesn’t appear to resolve anything. However, it does see an A record is present for it. Does Cloudflare give blank data back for private/reserved IP ranges? I was hoping that it would resolve to my 172.16.0.1 address, and then I could use that to connect to my device that’s plugged in.