Bug #449

DNS lookups for certain domains fail behind CeroWRT DNS

Added by Ethan Blanton on Jan 24, 2015. Updated on Jun 16, 2015.
Closed Normal Petri Rosenström


Several domains that I use regularly will not resolve when proxied by my CeroWRT 3.10.48-2 router, and nor will they resolve from the CeroWRT network diagnostics page. When setting the resolv.conf of a host behind my router manually to point to a known good resolver, however, they resolve correctly.

I have not been able to determine what causes this.

The symptoms from the client are that queries are sent to the CeroWRT device but it never returns a response. Compare this failing lookup:

16:51:36.140676 IP > 27175+ A? debian.org. (28)
16:51:41.140752 IP > 27175+ A? debian.org. (28)
[no response]

With this successful lookup:

16:51:51.220838 IP > 55242+ A? psg.com. (25)
16:51:51.221277 IP > 55242 1/0/0 A (41)

Examples of domains that fail reliably are debian.org (as above) and lkml.org. I have not identified any specific feature of these domains’ records that may cause this, but I haven’t examined them closely.


Updated by Ethan Blanton on Mar 8, 2015.
I suspect, but do not know, that the problem is domains that declare an IPv6 nameserver. This seems to have a high correlation with problematic domains.
Updated by Dave Täht on Jun 16, 2015.
dnssec in this version of cerowrt should be disabled. Too many edge cases found.

No update planned to 2.73, which solved most of them.

Updated by Ethan Blanton on Jun 16, 2015.
Great! How do I disable dnssec?

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