Docker install | Top client 192.168.14.x a lot of docker.io queries?

[flinthamm]

On a fresh install of this brilliant project "Technitium" everything seems to be working. To begin with only my a small number of devices are configured to use the DNS server. After 48 hours the "Top client" is a 192.168.14.1 address which seems the be the internal IP address of the docker container? All the other clients are on the normal and different subnet and the numbers look sensible (over a day the top client is 130k vs the next client down which is only 40k queries).
When you look at the logs it looks like this IP address is constantly querying 3 main domains, namely docker.io, registry-1.docker.io and auth.docker.io but I do not understand why, other than perhaps the configuration? The "DNS Server local endpoints" and almost all settings are left at their default.

I'm hoping this is something obvious to someone that can point me in the right direction and apologies if this is a silly question but thought it was worth ask to at least narrow the scope of diagnosis :)

[ShreyasZare]

Thanks for asking. The DNS server's config is all fine and the issue you see here is your system specific one. This is not normally observed with any docker installation so it might be some issue with the docker running on the system.

Not sure what could be the cause of this issue. Do try to reboot and see if that fixes it. Try to update docker too if its not on latest release.

[flinthamm]

Thank you @ShreyasZare for your prompt response and helpful reply. Having an authoritative answer has helped switch the focus to Docker which I'll now investigate - if anything interesting come up that might help the community, I'll aim to come back here with the results :)

[flinthamm]

Further investigation revealed a ghost container which seemed to be related to Docker Swarm which was forcibly unjoined and this rogue service left over from a very old container instance pruned. This has completely cleared the issue.
Thanks once again for pointing me in the right direction. Keep up your great work!

[ShreyasZare]

You're welcome! Good to know you found and fixed the issue.