Custom DNS Set on SDK 3.1

RE: Custom DNS Set on SDK 3.1

Michal — Mon, 27 Oct 2025 05:08:33 GMT

Great, that does sound like it should be a solution.

You can also find some documentation on that here: https://docs.nordicsemi.com/bundle/ncs-3.1.0/page/nrf/libraries/modem/lte_lc.html

Best regards,

Michal

RE: Custom DNS Set on SDK 3.1

DamoL — Tue, 21 Oct 2025 11:19:58 GMT

Hi Michal,

Whilst searching for something else I stumbled across these Config options

CONFIG_LTE_LC_DNS_FALLBACK_MODULE=y
CONFIG_LTE_LC_DNS_FALLBACK_ADDRESS="8.8.8.8"

If I look at the LTC_LC Debug, I see

<dbg> lte_lc: dns_fallback_set: Fallback DNS address successfully set to 8.8.8.8

So I am assuming it works in the same way as the old fix.

However, as it's a fallback I cannot test whether this does fix the problem with certain networks, and I don't think I'll be able to convince my boss to give me a free holiday again.
I will try and get a test board sent over to our customer over there and see if they can test it for us.

Thanks,

Damien

RE: Custom DNS Set on SDK 3.1

Michal — Fri, 03 Oct 2025 11:26:10 GMT

Maybe you could check using Cellular Monitor and Wireshark if a test device is communicating with a chosen DNS server?

Best regards,

Michal

RE: Custom DNS Set on SDK 3.1

DamoL — Thu, 02 Oct 2025 13:13:58 GMT

Hi Michal,

Well I can try and work out why it is failing there, and if I do I will update this thread. However, I am not sure how I would test that it works. The only network I know of that has the DNS issue is a 1 hour plane journey away, so ideally I need a way to ensure it works before pushing FW updates to units on that network. Do you know of a way I can test this?

Thanks,

Damien

RE: Custom DNS Set on SDK 3.1

Michal — Thu, 02 Oct 2025 13:06:11 GMT

You're welcome.

Does that mean you're fine on your own, or anything more I should look into here?

And of course, if you have any more questions, please just ask us on DevZone. We're here to help.

Best regards,

Michal

RE: Custom DNS Set on SDK 3.1

DamoL — Thu, 02 Oct 2025 09:03:53 GMT

Thanks Michal,

CONFIG_NETWORKING=y
CONFIG_NET_NATIVE=y
CONFIG_DNS_RESOLVER=y
CONFIG_DNS_SERVER_IP_ADDRESSES=y
CONFIG_DNS_SERVER1="8.8.8.8"

After a bit of searching I found that this configuration builds with a 9160, and when I debug, it gets to this function in zephr/subsys/net/lib/dns/resolve.c

dns_resolve_init_default(dns_resolve_get_default());

But it gets a -13 error (EACCES - permission denied)

I will keep looking into it.

Thanks,

Damien

RE: Custom DNS Set on SDK 3.1

Michal — Wed, 01 Oct 2025 14:58:36 GMT

Hello Damien,

You could maybe try CONFIG_DNS_SERVER_IP_ADDRESSES

Best regards,

Michal