DNS not working over any VLAN

Networking & Firewalls
1

Hi,

I have a 2 Vlan on top of my LAN interface and for some reason, all the devices on the vlan and ping via IP but not via FQDN. I don’t understand why. Could anyone please help?

Thank you

2

Need more info on the setup

What firewall, have you configured the vlan networks correctly - gateway, dns servers. Any rules that maybe blocking dns queries

What system is doing your dns queries - do you have pihole

On the machine in question,

  1. can you ping the dns server
  2. if you run nslookup , do you response back from queries
3

each VLAN needs DHCP configured for that subnet.

LAN ...    10.0.0.1   DHCP 10.0.0.100-200
VLAN25 ... 10.0.25.1  DHCP 10.0.25.100-200
VLAN40 ... 10.0.40.1  DHCP 10.0.40.100-200
4

I had that exact problem when I tried to use Kea DHCP. Reverting back to ISC DHCP (even though it says it will soon be deprecated) solved the issue for me.