PTR record handling in a subnetted network
David Tonhofer
david.tonhofer at synapse.lu
Fri Mar 2 22:43:44 UTC 2001
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
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