Untangle not handing out Secondary DNS in DHCP lease

[tescophil]

I'm sure this used to work, but under the network DHCP config I supply two comma sepapated IP addresses in the DNS Override field for Primary and Secondary DNS. However, when I look at a client device, only the primary (first) DNS address is set.

On version 16.2

Screenshot from 2021-01-27 23-40-29.png

[jcoffin]

Unfortunately two DNS overrides are not allowed. You will need to use DHCP / DNS options in Config -> network -> Advanced -> dns_and_dhcp

[sky-knight]

Use option 6!

In the DHCP options at the bottom of the screen you shotted, add one.

description can be anything, value is 6,192.168.10.35,192.168.10.36

[tescophil]

Yep, tried option 6 as soon as the first method failed, same result...

[tescophil]

Cool, tried option 6 under DHCP options which did not work. Could you provide an example of the option to set under Advanced Networking ?

[sky-knight]

You're going to have to do some more testing... because the option fields create the syntax that you'll need in the advanced section.

What are you getting in your DHCP lease?

building the option as I described will result in the following line in /etc/dnsmasq.conf

dhcp-option=tag:eth1,6,192.168.10.35,192.168.10.36

Which is incidentally... exactly what you'd have to put in the advanced tab feature. The only variation is the tag changes to match the eth interface you're working with.

*Edit*

Scratch all this, I was able to stuff a comma separated list of DNS addresses in the DNS Override field and achieved the same result. So yes, that should work too.

And... tossed 8.8.8.8,4.4.4.4 into the DNS override field, saved, ipconfig /release renew and my bench has the two above addresses ind the DNS list.

So yes, just put the comma separated list into the field and save it.

If you want to verify the configuration you can ssh in and cat /etc/dnsmasq.conf

I've got this working in several places because this is how I configure an Untangle branch office to support an AD over a VPN tunnel. It's worked for literally years, I just forget I've done it.

I think JCoffin is recalling a limitation in SDWAN? Because it's not in NGFW.

Again, sorry about that... do the easy thing a comma separated list like what you've got up there does work.

[tescophil]

Hi Rob, Yes.., that's exactly what I did, but still get just a single DNS server set..., something weird going on and it's almost 1am here, will revisit in the morning !

Something is getting cashed someherer among the line, as I can delete the override completely and my phone still gets the DNS server address I just deleted when renewing the DHCP lease.

[sky-knight]

Don't test with a phone... those things are horrible. Test with Windows or Linux on a real computer.

You have to hard boot your phone if you want to renew the DHCP lease, no amount of button pushing in the software works reliably.

[tescophil]

Morning has come and all is now well with the world, and DNS...

[sky-knight]

Morning has come and all is now well with the world, and DNS...

I blame the phone... it's always the stupid phone! And of course when it isn't... it's DNS. In this case we had BOTH + a late night?

Ouch... just ouch.