PTR record handling in a subnetted network

[David Tonhofer]

Concerns:   Handling of PTR records in BIND 9.1.0 in a subnetted network,
            to be precise, 194.154.217.224/28

Question:   No precise question, but does anyone have a comment on my
            big question mark at the end?

Background: This is a subsubnet in subnet 194.154.192.0/19 owned by the
            local telecom provider, P&TLuxembourg.

            I have recently replaced bind 8 by bind 9, and started looking
            for no particular reason at the reverse lookup, which I
inherited
            from the previous sysop.

We see the following in the reverse lookup database record:

-------------------
$TTL 28800
$ORIGIN 217.154.194.in-addr.arpa.
224             IN      SOA     dns1.synapse.lu. dnsadmin.synapse.lu. (
                2001020406 28800 7200 604800 86400 )
                IN      NS      dns1.synapse.lu.
                IN      NS      dns2.synapse.lu.
$ORIGIN 224.217.154.194.in-addr.arpa.
225             IN      PTR     dns1.synapse.lu.
(etc)
--------------------

This worked for bind 8 and also works for bind 9, but it's not how
things should be according to RFC2317

  http://www.cis.ohio-state.edu/htbin/rfc/rfc2317.html

Notice the second $ORIGIN which actually gives the base address of my
network. Question: do I have to set it up like this because my
provider is doing something wrongly/weirdly? I tried some other approaches
but mainly got 'out of zone' errors from BIND.

Using the above setup, I do:

---------------------
host -v 194.154.217.225
Trying "225.217.154.194.in-addr.arpa."
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 44026
;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 2

;; QUESTION SECTION:
;225.217.154.194.in-addr.arpa.  IN      PTR

;; ANSWER SECTION:
225.217.154.194.in-addr.arpa. 68781 IN  CNAME
225.224.217.154.194.in-addr.arpa.
225.224.217.154.194.in-addr.arpa. 28800 IN PTR  dns1.synapse.lu.

;; AUTHORITY SECTION:
224.217.154.194.in-addr.arpa. 28800 IN  NS      dns2.synapse.lu.
224.217.154.194.in-addr.arpa. 28800 IN  NS      dns1.synapse.lu.

;; ADDITIONAL SECTION:
dns1.synapse.lu.        28800   IN      A       194.154.217.225
dns2.synapse.lu.        28800   IN      A       194.154.217.229

Received 162 bytes from 127.0.0.1#53 in 4 ms
---------------------

Or, more briefly:

---------------------
$host 194.154.217.225
225.217.154.194.in-addr.arpa. is an alias for
225.224.217.154.194.in-addr.arpa.
225.224.217.154.194.in-addr.arpa. domain name pointer dns1.synapse.lu.
---------------------

Question: *Who* says that

"225.217.154.194.in-addr.arpa. 68781 IN  CNAME
225.224.217.154.194.in-addr.arpa."

because it's definitely not my nameserver...is it?


Thanks in advance for any answer.

-- David Tonhofer