Android DNS - doesn't use nameserver on LAN?

[#1]

Hi all,

I've got my DHCP server working in order to hand out the IP of my nameserver which hosts several domains internally on our network. This works fine on windows machines, they do as they're told and use my nameserver and everything is ticketyboo.

On our android devices name resolution drops dead. On the GUI for my nameserver I can see that a request comes in, and that one is issued, wireshark confirms it was replied to and that the packet conforms but android keeps saying that it cannot resolve the domain.

When i set the nameserver ip back to the router (or an external IP) all is good again. It seems that it is only a lan problem where android deliberately refuses to act on information being returned from a nameserver that is on a different IP to the router / gateway. I've even tried the spare wifi AP in case it was getting upset about the nameserver being a hop further away than the router but it still didn't like it.

So my question.. is this a known android thing? - I've found a few references to it online but all the symptoms seem to vary slightly (though pi-hole users have been complaining). I'm just wondering if there is any sort of workaround other than using an external nameserver with internal A records which isn't ideal..

[#2]

Yep seen this on mine. I think there is a dns changer on the play store, but it may require root access, but not tried it I just use ip addresses.

[#3]

Could you set the router's DNS to point at your internal nameserver.

Therefore your Android will request from router, that will in turn ask your nameserver, which will get it's info from your WAN bypassing the router.

If your nameserver is caching, then that will still be faster than Android using the router alone.

It may or may not work with your router, but it would work with mine.

[#4]

We use the hub one which means i can't do that - plusnet lock the thing so you can't change dns.

[#5]

Just to be clear, if you manually configure your Android device to use your local nameserver (not the router) for DNS resolution then that also doesn't work? Or is it only when forcing the configuration via DHCP that you are having problems?

[#6]

You could disable the dhcp server on the Hub 1 and use the pi-hole to do both. That MAY fix it.

[#7]

I had assumed that's how it was configured, otherwise having two DHCP servers on the LAN is going to cause issues.

[#8]

Just used DNS Changer (non root) from the play store. Changing to my pi-hole server dns let me use http://pi.hole as an address (you have to use http://or google grabs the query) if you don't want to use pi.hole as a dhcp server.

[#9]

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@MJN wrote:

Just to be clear, if you manually configure your Android device to use your local nameserver (not the router) for DNS resolution then that also doesn't work? Or is it only when forcing the configuration via DHCP that you are having problems?

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Manual configuration never worked either.

Yes hubone DHCP was turned off during trials.

Will give pi-hole trial a go at some point, be interesting to see if android can see it!

EDIT: Guys you're confusing me lol. Android can see the nameservers, it's just refusing to act on the returned results for whatever reason as i previously stated. I'm going to try the app HMcB has recommended and see if that makes any difference but i have a hunch this is an android glitch or security 'feature'.

[#10 · Accepted solution]

Ok I've got this fixed!!!

My dns server wasn't setting the RClass in the returned resource records. I've updated that and now it sets the results to 1 for IN and everything works on android devices as it should. Android DOES use local nameservers it's just a bit pickier than windows which apparently doesn't worry about the RClass.

Good old wireshark.. 

Sorry that doesn't help you @HairyMcbiker, no idea whats up with pi-hole

[#11]

Is this DNS server one you've written yourself? If so you really ought to have made that clear from the outset!

[#12]

I had always assumed that this topic was about a self written DNS / DHCP project

[#13]

There's nothing suggesting that in the thread.

[#14]

That may be so, but this is @7up , and he does have a history of doing such things - which is fine ! 

[#15]

Ah, okay, I'll bear that in mind in future! 😉