OpenThread DNS Service Discovery only every returns one result, how to get all results on the network?

[kylekufalk-metropolis]

On the device we're developing (small battery powered sensor tag, Thread Sleepy End Device usinc NCS v2.7.0), when trying to discover DNS services using the `otDnsClientBrowse()`, it only ever returns one result even if multiple are on the network. On my test network, the tag can both services on the network but appears to only return the first one it finds. In the attached screenshot, you can see the CLI example code from the v3.2.2 SDK seeing both services on the network, but only returning one at a time.

This can be worked around by calling `otDnsClientBrowse()` multiple times, this however isn't deterministic or efficient. Is there a way to do a browse that returns all of the available services on the network? Here's the browse done on my dev machine using Avahi for reference. 

[Amanda Hsieh]

Hi Kyle, 

It seems that implementation prints everything it gets (also multiple services). Can you ensure that the node gets more than one service in the DNS Response by using Sniffer? Maybe the server returns just one.

Regards,
Amanda H.

[kylekufalk-metropolis]

Hello Amanda, 

It does look like the server only returns one instance (attached is the packet capture). Perhaps a little out of scope for this forum, but we compile the ot-br from source. Is there an option we can enable to force it to send all instances?

Thanks,

Kyle Kufalk

ot_dns_browse_one_result.pcapng

[Amanda Hsieh]

How do you run ot-br and from which commit? Can you do `avahi-browse` from within OTBR?

[kylekufalk-metropolis]

I followed the instructions for native install on the OpenThread website: https://openthread.io/guides/border-router/build-native

The commit returned from `ot-ctl version` is 3702c88 about a year and half old. 

Unsure how to run `avahi-browse` from within the border router itself, but the `avahi-browse` screenshot attached on the original post is from the host machine. I can also confirm that the border router sees both instances, when I run a browse from the edge device both show up in the border router logs: 

[Amanda Hsieh]

Then maybe it would be a good idea to first check if the problem still exists on the newest OT BR first.

As this issue is unlikely to be caused by our devices, it's more about the configuration. Therefore, I would suggest you post an issue here: https://github.com/openthread/ot-br-posix/issues or here: https://github.com/orgs/openthread/discussions

[kylekufalk-metropolis]

Checked and it unfortunately persists on the latest OpenThread code. I'll post an issue on their repos. Thanks for your help Amanda!