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DNS requests from Android v5 (and newer) fail for internal sites only

Posted on 2016-08-03
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Last Modified: 2016-11-22
We've been experiencing a very specific issue for almost a year, and it's finally becoming problematic for us.  All Android devices running v5 (Lollipop) and newer are unable to view internal web sites.  Browsing the public internet has no issue.

Digging further, we determined that the Androids are not able to resolve internal names.  Further, a sniffer shows that the Android phones are ignoring the DNS server entries in the DHCP settings, and instead use Google's public DNS (8.8.8.8) for all name resolution--hence, no ability to resolve internal names.

We've confirmed that the devices are receiving the correct DHCP entries for DNS, the phones just aren't using it.

We have a Windows Server 2012 network, single-domain, with three sites (subnets) and four DC's, all of which are our DNS hosts.  Our wireless access points are Dell PowerConnect-W model AP-105 (by Aruba Networks).

I've found internet information that seems to indicate that this might be related to IPv6 issues between Android v5(+)  and IPv4 DNS:
https://code.google.com/p/android/issues/detail?id=79504

I've focused on this because our network has had IPv6 entirely disabled (against Microsoft Best Practices recommendations) via Group Policy.  If we need to re-enable/implement IPv6, that will be a challenge in the existing environment.

Can anyone provide insight on what may be the underlying issue(s) here, and how we might address it?

Please let me know if there's any further information I can provide.

Thank you.

Dimarc67
Frederick, MD
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Question by:Dimarc67
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giltjr earned 500 total points
ID: 41742258
Reading https://code.google.com/p/android/issues/detail?id=79504 it seems that the problem was that the domain name provided by DHCP was not being propagated to the resolver.  See post #3.

The IPV6 vs. IPV4 issue does not seem to be a bug, but just the fact that new versions of Android will try to use IPV6 to resolve names first and then try IPV4.

What is weird is the last post states that a stock Andriod does not use 8.8.8.8 unless tethered and then only as a last resort.

However, other than politics, enabling IPV6 should not be a big issue.  It only needs to be enabled on your DNS servers.  Normal desktops and servers that don't provide DNS services don't need IPV6 enabled.  That should drastically reduce the impact of enabling IPV6 if that is the only fix.
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by:giltjr
ID: 41742265
Also found  this post,.  I have not read the whole thing, as this one goes back to 2010 and has almost 300 entries.  Most recent being June of this year.

https://code.google.com/p/android/issues/detail?id=8030
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by:Jackie Man
ID: 41743580
How is the setup of your DNS server?

My finding for an workaround is as follows:-

"The workaround is to set a gateway in the DHCP. This way android sends both AAAA and A queries for an android device."

Source: https://www.centos.org/forums/viewtopic.php?t=8269
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by:Jackie Man
ID: 41743582
The other workaround is to use Firefox app in Android to access your local site instead of Chrome.

http://stackoverflow.com/questions/8651043/android-browser-hostnames-does-not-get-resolved-if-domain-name-is-not-appended
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by:Dimarc67
ID: 41747264
Thanks.  Confirmed the IPv6 behavior for DNS in Android v5 and newer.  (Also could not confirm that Firefox on Android got around the issue.  That didn't work for us.)

Enabling IPv6 on our DNS servers (our DCs) appears to be the best solution.
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by:Dimarc67
ID: 41790351
Further testing may eliminate the IPv6 hypothesis.  

Tested the same Android v5 device that was experiencing the issue at a different site, and issue did NOT recur.  No huge differences between the two sites except Win2012 vs. 2008R2, Cisco vs. Linksys router, and Aruba vs. Linksys WAP.

Enabled IPv6 on office Windows DNS server, successfully resolved DNS host names via IPv6 through Android app "DIG" on test device.  Still unable to reach internal site names through browser.

Windows DNS debug logging too sporadic to make immediate go/nogo determinations.

Will need to setup a sniffer to see the traffic in real-time.  Will post findings when I get there.
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