Thanks for confirming bind behavior matches what I saw. I noticed other resolvers (eg: @8.8.8.8) works differently, c.b.a.com NS host2 actually got used, not ignored as occluded data. Is this a bind specific implementation, not required by any RFCs? >From authoritative dns perspective, Amazon Route53 allows you to add both delegations in the a.com zone without any "out of zone data" error.
On Tue, Nov 13, 2018 at 1:50 PM Mark Andrews <ma...@isc.org> wrote: > > > On 14 Nov 2018, at 4:04 am, Frank Liu <gfrank...@gmail.com> wrote: > > > > Hi, > > > > Is there a RFC determining which nameserver to use if there is a > conflicting subdomain delegation? > > > > eg: > > In the zone of a.com, there are two NS delegations > > This one is used. > > > b.a.com NS host1 > > This one is ignored as it is occluded data. > > > c.b.a.com NS host2 > > > > On host1 in zone b.a.com, there is > > c.b.a.com NS host3 > > Which is occluded data or glue depending upon the rest of the contents of > the zone. > > > As you can see, there is a conflicting delegation for c.b.a.com. If I > look a name d.c.b.a.com, will the nameserver host2 or host3 be used? > > dig +trace seems to go to host2, but bind9 as a resolver goes to host3. > > (the test was done on a centos7). > > dig +trace follows the returned delegations. > > > Any ideas? > > Thanks! > > _______________________________________________ > > 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 > > -- > Mark Andrews, ISC > 1 Seymour St., Dundas Valley, NSW 2117, Australia > PHONE: +61 2 9871 4742 INTERNET: ma...@isc.org > >
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