Strange DNS PTR records

Sat Jun 8 22:19:03 MDT 2013

Am Donnerstag, 6. Juni 2013, 21:23:42 schrieb Charles Tryon:

Hello Charles,

> More information:
> 
> On Thu, Jun 6, 2013 at 11:04 AM, Charles Tryon <charles.tryon at gmail.com>wrote:
> > OK, I've partially answered my own question, but now I have another...
> > 
> > I found that I can remove the entire reverse lookup zone through the MS
> > tool, without it throwing fits or the exist/doesn't exist catch 22.
> > 
> > However, when I run my rebuild script to add the PTR records back in, I
> > get the following:
> > 
> > (these are the
> > /usr/local/samba/bin/samba-tool dns zonecreate samba 4.10.in-addr.arpa
> > /usr/local/samba/bin/samba-tool dns add samba 4.10.in-addr.arpa 25.0 PTR
> > something.mydomain.org
> > /usr/local/samba/bin/samba-tool dns add samba 4.10.in-addr.arpa 26.0 PTR
> > nas1.mydomain.org
> > /usr/local/samba/bin/samba-tool dns add samba 4.10.in-addr.arpa 100.2 PTR
> > vmhost.mydomain.org
> > etc...
> > 
> > Remember that I'm using a /19 subnet.  This creates folders for "0" and
> > "2", and then creates PTR records like 10.4.0.0.25 and 10.4.2.2.100.
> > 
> > I'm assuming my problem is in how I'm calling the samba-tool, but I'm not
> > clear on the directions for when you are working with something other
> > than a 255.255.255.0 subnet.
> 
> The problem is definitely in how the zone is getting created by the
> samba-tool dnz zonecreate command.  I deleted the entire reverse zone
> again, and then used the Zone Create wizard on the Windows DNS admin tool
> to create just the empty zone.  Since I only specified "10.4" for the
> subnet (which still isn't strictly correct, since this usually means a /16
> or 255.255.0.0 net mask), it didn't try to create a /24 subnet, with
> folders under that.  When I used exactly the same samba-tool commands to
> create the individual PTR records, the were all created correctly (for
> example, 10.4.2.100), and now work as expected.
> 
> So, it there an option on the samba-tool zonecreate command that allows you
> to use a specific subnet mask?
> 
> Output from the samba-tool query:
> <samba:dev>? samba-tool dns query samba 4.10.in-addr.arpa @ ALL
>   Name=, Records=2, Children=0
>     SOA: serial=62, refresh=900, retry=600, expire=86400, minttl=3600, ns=
> samba.usa.om.org., email=hostmaster.usa.om.org. (flags=600000f0, serial=62,
> ttl=3600)
>     NS: samba.usa.om.org. (flags=600000f0, serial=1, ttl=3600)
>   Name=0, Records=0, Children=34
>   Name=1, Records=0, Children=18
>   Name=2, Records=0, Children=9
> 
> > On Wed, Jun 5, 2013 at 4:18 PM, Charles Tryon <charles.tryon at gmail.com>wrote:
> >> Another question regarding DNS:
> >> 
> >> I have a test domain I provisioned quite a while ago (probably shortly
> >> before the final 4.0.0 release, but I don't remember exactly when).  It
> >> is currently set up to use BIND 9.9 for DNS.  Most things are running
> >> fine on it (though admittedly it doesn't get pushed very hard).
> >> 
> >> When I look at the domain using the DNS manager from Windows Remote
> >> Management Tools set (from a Win7 client), I the forward lookup zone
> >> looks fine, but I see a bunch of strange PTR records.  Almost all the
> >> PTR records have five octets rather than the normal four -- for
> >> example, 10.4.0.0.100, or 10.4.2.2.10.  In all cases, the third and
> >> fourth positions are the same.
> >> 
> >>  (We are using a /19 subnet.)  The really bizarre thing is that if I try
> >>  to
> >> 
> >> delete the records, I get an error back that the records "do not exist."
> >> 
> >> Is this an example of the "zombie DNS records" which I've seen mentioned
> >> here?
> >> 
> >>  - If it is, what is the best way to clean this up?
> >>  - If I use the "samba_upgradedns" command, will that purge/rebuild/fix
> >> 
> >> the DNS database, or will it simply change the front end (BIND vs.
> >> Internal) server which is looking at the same back end database?
> >> 
> >> (Re-provisioning this box from scratch isn't entirely out of the
> >> question, since it is a test server, but it would be a big pain to
> >> reconstruct the domain, especially the machine accounts.  :-( )
> >> 
> >> Thanks!

I did some first tests here and i think that something is working completely
wrong.....

Btw - do you use the internal dns server or the samba BIND DLZ plugin?

I'll keep you informed about my further findings.

Your usage of a /19 subnet is a completely different story.
So first of all the minimal basics should work.

Additional readings about CIDR regarding (subnetted) reverse zones:
http://tools.ietf.org/html/rfc2317
http://serverfault.com/questions/22743/reverse-dns-in-a-cidr-world?lq=1
http://support.microsoft.com/kb/174419/en-us

All this is very special - and i guess - has never been tested with samba.
At least the internal dns server will have problems with CNAME records
pointing outside the handled zone ...

Btw - why did you use a /19 subnet?

I keep you informed.

Cheers, Günter