On Tue, 2013-06-25 at 17:07 +0100, Steven Carr wrote: > 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 > Ah, that is what I was wondering. Thanks.
> 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. > Yes, I did try that. Cleared the cache, then ran 'rndc dumpdb' after the first query, saved the file then ran it again after a second query. Unfortunately I couldn't see our internal servers being cached at all (which they should have been after the first query). At that point I thought I'd ask on the list. I'll repeat the testing to see if I can see what is going on. John. -- John Horne, Plymouth University, UK Tel: +44 (0)1752 587287 Fax: +44 (0)1752 587001 _______________________________________________ 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
