On 25 June 2013 16:53, John Horne <john.ho...@plymouth.ac.uk> wrote: > So what I now do not understand is why (at home) I can do several > reverse lookups for different IP addresses, and they all give me an > answer. Likewise if I do something like: > > dig -x 141.163.99.16 @8.8.8.8 > > I get a non-authoritative answer. If I repeat this for addresses > 141.163.99.17, 18, 20 and so on I get answers. In all these cases > shouldn't the first lookup work and subsequent ones fail? Using Google's > name server, shouldn't it at some point have received the authoritative > answer with the AUTHORITY section NS records and so be using those > (internal) name servers for subsequent lookups?
Using Google you will get unexpected results, not sure exactly what caching engine they use but it doesn't work like most other caching servers, they definitely do some jiggery pokery with the results (I've seen Google continue to return correct results for domains that had completely corrupted NS records both in the parent and authoritative). I would suggest you install a local copy of BIND configured for recursion and let it do the queries for you then you can also use rndc to inspect the cache for yourself. Steve _______________________________________________ Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list bind-users mailing list bind-users@lists.isc.org https://lists.isc.org/mailman/listinfo/bind-users
