I need some help, if posible, to understand some strange situation. Unfortunately we can give a method to reproduce it, but we have some hard data.
We have a couple of dnsdist servers. Half 1.1.0 and half 1.3.2, moving from old to new. The 1.1.0 are still getting most of the traffic and the problem happens there. The user base is 100% mobile, and we serve more than 200kqps We received complains about domain names unresolved which do exist. first time, ignored, second time some checks, third time more checks. The problem gets solved expunging the cache. All fine BUT, during our checks we noticed inconsistent behavior of the cache regarding this names. Android chrome access to page -> fails. AndroDNS (dns tools) query standard -> empty answer query over TCP -> correct answer query whith DO -> correct answer query whith CD -> correct answer Checking from Linux: host command: -> empty answer host over TCP -> correct answer dig command -> correcto When the cache is cleared, all works OK. We asume that there is some situation with the domain which create wrong cached entries, but why we have different answers from UDP than from TCP? the query flags are exactly the same (0x0100) And why the difference between host and dig (the only difference at paquet level is the AD bit set on DIG, 0x0100 vs 0x0120) If anybody can help a little..... Thanks!!
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