[Bug 1466608] Re: Unable to resolve domains with large EDNS0 replies
Ketil
1466608 at bugs.launchpad.net
Thu Jun 18 23:03:38 UTC 2015
Thanks, I was hoping for some help to find the right place to report
this.
I poked around some more, and I found out what the problem was. First of
all, my wireless router was confused. I rebooted it, and then everything
started working again.
I did some debugging before I rebooted it, though, and the reason for
the partial failure situation was that EDNS0 wasn't specified in the
queries sent by Ubuntu, but dig specifies it by default (as well as the
AD flag, but I don't think that's relevant). A partial result should
have been given by the DNS server (on the wireless router), or it should
have truncated the reply to force a TCP retry by the client. (Now that
everything works, it trims down the Additional section to fit the
response.) To confirm, I ran dig like this, and these queries failed on
my confused router:
dig +noedns +noadflag @127.0.1.1 www.sciencedaily.com
So if Ubuntu had in fact set EDNS0 in the query, it would have worked.
Falling back to TCP presumably wasn't an option since no
malformed/truncated result was received first.
Feel free to close this issue if my router's behaviour was completely
unacceptable and should cause failure on the client side. If it ought to
have been handled better by Ubuntu, however, this may have been an
interesting corner case for debugging.
Let me know if you need anything else.
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https://bugs.launchpad.net/bugs/1466608
Title:
Unable to resolve domains with large EDNS0 replies
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