Clarification on wildcard falls into glue records
dot at dotat.at
Tue May 15 14:53:41 UTC 2012
Sam Wilson <Sam.Wilson at ed.ac.uk> wrote:
> Is a name on the RHS of an RR regarded as existing enough to prevent
> wildcard lookup?
No, only RR owner names.
> In this I would have expected the NS lookup to be followed by an A
> lookup for abc.a.example.com which would match the wildcard, assuming no
> other records match that name on the LHS.
Yes that should work. The latter answer might appear to be missing because
additional section processing is a bit special. In your original question
you mentioned glue, which is only necessary for delegations above the zone
cut, and probably should not rely on wildcards. If this is a zone apex NS
RRset then the server doesn't have to fill in the additional section. See
the example below, from a nameserver that has minimal-responses turned on.
; <<>> DiG 9.8.1-P1 <<>> ns dotat.at
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 41609
;; flags: qr aa rd ra; QUERY: 1, ANSWER: 4, AUTHORITY: 0, ADDITIONAL: 0
;; QUESTION SECTION:
;dotat.at. IN NS
;; ANSWER SECTION:
dotat.at. 3600 IN NS ns1.gratisdns.dk.
dotat.at. 3600 IN NS black.dotat.at.
dotat.at. 3600 IN NS puck.nether.net.
dotat.at. 3600 IN NS ns3.gratisdns.dk.
;; Query time: 1 msec
;; SERVER: 127.0.0.1#53(127.0.0.1)
;; WHEN: Tue May 15 15:52:19 2012
;; MSG SIZE rcvd: 123
f.anthony.n.finch <dot at dotat.at> http://dotat.at/
Forties, Cromarty, Forth, Tyne, Dogger: Northwest 5 to 7, occasionally 4 in
Forth and Tyne. Moderate or rough, occasionally very rough in Forties and
Dogger. Showers. Good, occasionally moderate.
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