Win2K3 revDNS problem

Hello,

At the beginning, I'd like to apologise for my bad english, but it's
not my native language.

I have a strange problem with DNS service.

There is a local network 192.168.1.0/24 with internet access through a
router (Cisco 1600). Router translates local adresses to external ones
(let's say xxx.xxx.xxx.0/24) for a few computers (servers).

Computer with address 192.168.1.202 (external xxx.xxx.xxx.204) has a
DNS service running on Windows 2003 SP1. DNS service works without any
problems translating symbolic adresses to numeric, but there is a
problem with opposite direction, but only when I ask server using
external address, for example:

$ host -a xxx.xxx.xxx.204 192.168.1.202

[ everything is ok ]

$ host -a xxx.xxx.xxx.204 xxx.xxx.xxx.202

Trying "204.xxx.xxx.xxx.in-addr.arpa"
;; Got bad packet: bad compression pointer
121 bytes
aa eb 81 83 00 01 00 00 00 01 00 00 03 32 30 34
02 36 38 02 39 38 03 32 31 37 07 69 6e 2d 61 64
64 72 04 61 72 70 61 00 00 0c 00 01 c0 12 00 06
00 01 00 01 4f bc 00 41 08 70 72 69 73 6f 6e 65
72 04 69 61 6e 61 03 6f 72 67 00 0a 68 6f 73 74
6d 61 73 74 65 72 0c 72 6f 6f 74 2d 73 65 72 76
65 72 73 c0 46 77 54 b7 e0 00 00 07 08 00 00 03
84 00 09 3a 80 00 00 01 90

It's very strange for be, because server don't know that it has also
external address (server address is 192.168.1.202, router makes a
translation). It's strange even more, because translating symbolic
addresses to numeric works well regardless of I use local or external
IP address.

So, what is a reason of this problem?

Best Regards,

Bogdan Modzelewski

Your local DNS server will have two zones. One is the normal zone which
translates names to IP addresses for local machines. The other is a reverse
lookup zone which translates IP addresses to names. (This is the one with
..arpa at the end).

For local machines, this is all that you need. Your local names can be
translated to their local private addresses (192.168.1.0/24) and these
addresses can be translated back to local names by the reverse lookup zone.

Your local DNS server will not have a reverse lookup zone for your
server's public IP address. The reverse lookup zone for that IP will be on a
public DNS server (probably at your ISP).

Do your client machines (and the DNS server itself) use your local DNS
only? Is it configured to forward DNS requests to a public DNS service?

PS. I have no problem at all with your English!

<(E-Mail Removed)> wrote in message
news:(E-Mail Removed) ups.com...
> Hello,
>
> At the beginning, I'd like to apologise for my bad english, but it's
> not my native language.
>
> I have a strange problem with DNS service.
>
> There is a local network 192.168.1.0/24 with internet access through a
> router (Cisco 1600). Router translates local adresses to external ones
> (let's say xxx.xxx.xxx.0/24) for a few computers (servers).
>
> Computer with address 192.168.1.202 (external xxx.xxx.xxx.204) has a
> DNS service running on Windows 2003 SP1. DNS service works without any
> problems translating symbolic adresses to numeric, but there is a
> problem with opposite direction, but only when I ask server using
> external address, for example:
>
> $ host -a xxx.xxx.xxx.204 192.168.1.202
>
> [ everything is ok ]
>
> $ host -a xxx.xxx.xxx.204 xxx.xxx.xxx.202
>
> Trying "204.xxx.xxx.xxx.in-addr.arpa"
> ;; Got bad packet: bad compression pointer
> 121 bytes
> aa eb 81 83 00 01 00 00 00 01 00 00 03 32 30 34
> 02 36 38 02 39 38 03 32 31 37 07 69 6e 2d 61 64
> 64 72 04 61 72 70 61 00 00 0c 00 01 c0 12 00 06
> 00 01 00 01 4f bc 00 41 08 70 72 69 73 6f 6e 65
> 72 04 69 61 6e 61 03 6f 72 67 00 0a 68 6f 73 74
> 6d 61 73 74 65 72 0c 72 6f 6f 74 2d 73 65 72 76
> 65 72 73 c0 46 77 54 b7 e0 00 00 07 08 00 00 03
> 84 00 09 3a 80 00 00 01 90
>
> It's very strange for be, because server don't know that it has also
> external address (server address is 192.168.1.202, router makes a
> translation). It's strange even more, because translating symbolic
> addresses to numeric works well regardless of I use local or external
> IP address.
>
> So, what is a reason of this problem?
>
> Best Regards,
>
> Bogdan Modzelewski
>

Bill Grant wrote:
> Your local DNS server will have two zones. One is the normal zone which
> translates names to IP addresses for local machines. The other is a reverse
> lookup zone which translates IP addresses to names. (This is the one with
> .arpa at the end).

Yes, that is clear for me.

> For local machines, this is all that you need. Your local names can be
> translated to their local private addresses (192.168.1.0/24) and these
> addresses can be translated back to local names by the reverse lookup zone.

I don't use DNS service for translating local names at all. It's using
only for translating external addresses (for example it contains
information about www or mail server for my domain).

> Your local DNS server will not have a reverse lookup zone for your
> server's public IP address. The reverse lookup zone for that IP will be on a
> public DNS server (probably at your ISP).

Yes, but my ISP redelegate/redirect (I don't know correct terminology)
reverse queries for my whole C class subnetwork to my DNS server. Maybe
I'm not precise enough - I have C class subnetwork (255 external
addresses) from my ISP, that are translated by Cisco router to local
(192.168.1.0/24) addresses. Of course it's not one-to-one mapping,
workstations are not visible from outside, but servers (including DNS)
are.

> Do your client machines (and the DNS server itself) use your local DNS
> only? Is it configured to forward DNS requests to a public DNS service?

Yes. As I've written before forward queries from outside works without
any problems. Problem is only with reverse queries and only when I ask
server with its external address. To summarize:

query about
xxx.xxx.xxx.204 (mail.mydomain.pl)
[ My Workstation (192.168.1.142) ]
<--------------------------------------------------------------------->
[ DNS (192.168.1.202) ]

works for both forward and reverse queries (xxx.xxx.xxx.204 is external
mail server address).

But when I ask DNS server with its external address (so query have to
go through the router):

[ My Workstation (192.168.1.142) ] <----> [ Router (192.168.1.1 /
xxx.xxx.xxx.1) ] <----> [ DNS (xxx.xxx.xxx.202) ]

It works for forward queries only. Any reverse query returns "Got bad
packet: bad compression pointer" error message I've attached in
previous post.

> PS. I have no problem at all with your English!

You're very kind, but my english is not as good as I'd like to.

Best Regards,

Bogdan Modzelewski