DNS problem

jamesdun

Hello,
I have a standard setup with pfSense as my firewall, router, and DNS server. I also manage my own domain, with DNS configured to serve internal addresses (like for mail). The public versions of these records point to my public IP through a Dynamic DNS service.

This configuration works for almost all my devices. For instance, my phone and laptop can access my email server whether they are connected to my internal LAN or using the internet while I'm away.

Recently, I added a new PC running Windows 11, and it seems to always resolve to my public IP during DNS lookups. It's using the same DNS server as my other devices, which is set via DHCP, and I’ve confirmed this with both ipconfig and NSLookup.

Does anyone have any ideas why this might be happening?

Gertjan

@jamesdun

What is the content of your /etc/hosts file ? Does this Windows 11 show up in there with the correct "RFC1918" LAN IP (and IPv6 if you use IPv6) ?

Did you set up a static mac lease for this PC ? The static lease is honored, aka : the PC got the IPv4 intended ?

You use KEA ? Did you activate under Services > DHCP Server > Settings the Early DNS Registration on the settings page and the LAN page ?

jamesdun

I actually noticed it when trying to set up an Outlook client on the new machine. I have flushed DNS a couple of times. Tests have been performed with NSLookup on both the new machine and an existing one. Both machines show the correct DNS server when NSLookup is launched, although the old one also gives it a name and the new one fails to do the reverse lookup. Then I enter the mailserver FQDN. New machine gives public IP, old one gives internal.

Additional info: Both machines are on the same network (wired ethernet - adjacent switch ports) and there are no vLANs involved.

It makes absolutely no sense to me! I could understand if the new machine wasn't picking up the correct DNS server, but that's not what the tools say....

Gertjan

@jamesdun

@jamesdun said in DNS problem:

if the new machine wasn't picking up the correct DNS server

Well, launch

ipconfig /all

and it tells you what DNS server it uses.
Normally, a new Windows PC will use DHCP is so it's 'plug and play'.

@jamesdun said in DNS problem:

Both machines show the correct DNS server when NSLookup is launched, although the old one also gives it a name and the new one fails to do the reverse lookup

Looks like the new machine isn't allowed to do DNS requests against pfSense ?

@jamesdun said in DNS problem:

and the new one fails to do the reverse lookup

Humm. The new one's DNS request gets refused ...