RE: MS-DNS Expert

ronb@SYSYGY.com.au
Thu, 24 Jul 1997 12:57:30 +1000

Hi

Well, you say that you are having reverse lookup problems. I have been
using MS DNS for about 6 months now, but I just noticed that I am
sometimes getting problems also with reverse lookups. It seems that the
problem is when a Unix-based DNS tries to do reverse lookups to a MS
DNS. I have ample details to explain my point below :

First we confirm that both forward and reverse lookups work fine from
one MS DNS to another.
So, as can be seen below, from my MS DNS, a *local* forward and reverse
lookup (zone defined locally) works fine :

==============================================

> nova.sysygy.com.au
Server: nova.sysygy.com.au
Address: 203.11.124.5

Name: nova.sysygy.com.au
Address: 203.11.124.5

> 203.11.124.5
Server: nova.sysygy.com.au
Address: 203.11.124.5

Name: nova.sysygy.com.au
Address: 203.11.124.5

>

==============================================

Now, from a remote MS DNS, *local* forward and reverse lookup (of their
own zone) works fine also :

==============================================

> server alphaserver.scottcarver.com.au
Default Server: alphaserver.scottcarver.com.au
Address: 203.62.162.2

> alphaserver.scottcarver.com.au
Server: alphaserver.scottcarver.com.au
Address: 203.62.162.2

Name: alphaserver.scottcarver.com.au
Address: 203.62.162.2

> 203.62.162.2
Server: alphaserver.scottcarver.com.au
Address: 203.62.162.2

Name: alphaserver.scottcarver.com.au
Address: 203.62.162.2

>

==============================================

And forward and reverse lookups from the remote MS DNS to my MS DNS
works fine (querying my local zone from the remote DNS) :

==============================================

> nova.sysygy.com.au
Server: alphaserver.scottcarver.com.au
Address: 203.62.162.2

Non-authoritative answer:
Name: nova.sysygy.com.au
Address: 203.11.124.5

> 203.11.124.5
Server: alphaserver.scottcarver.com.au
Address: 203.62.162.2

Name: nova.sysygy.com.au
Address: 203.11.124.5

>

==============================================

Here are further details of the successfull reverse lookup from the
remote MS DNS to my DNS :

==============================================

> 203.11.124.5
Server: alphaserver.scottcarver.com.au
Address: 203.62.162.2

------------
SendRequest(), len 43
HEADER:
opcode = QUERY, id = 32, rcode = NOERROR
header flags: query, want recursion
questions = 1, answers = 0, authority records = 0, additional
= 0

QUESTIONS:
5.124.11.203.in-addr.arpa, type = PTR, class = IN

------------
------------
Got answer (75 bytes):
HEADER:
opcode = QUERY, id = 32, rcode = NOERROR
header flags: response, want recursion, recursion avail.
questions = 1, answers = 1, authority records = 0, additional
= 0

QUESTIONS:
5.124.11.203.in-addr.arpa, type = PTR, class = IN
ANSWERS:
-> 5.124.11.203.in-addr.arpa
type = PTR, class = IN, dlen = 20
name = nova.sysygy.com.au
ttl = 85715 (23 hours 48 mins 35 secs)

------------
Name: nova.sysygy.com.au
Address: 203.11.124.5

>

================================================================

Ok.....So everything seems to be working just fine from MS DNS to
another MS DNS. So "what's the problem?" , you may ask. Well, the
problem is when I try to do remote reverse lookups from a Unix-based DNS
to a MS DNS, as the following will show :

Doing reverse lookups fails, but forward lookups work fine. This was
tested from the Unix-based server to both : 1) my local MS DNS, and 2)
another remote MS DNS. Both reverse lookups failed, but forward lookups
were fine.

(Note : 203.12.160.1 is a Unix-based DNS)
==============================================

> server 203.12.160.1
Default Server: brand.tpgi.com.au
Address: 203.12.160.1

> nova.sysygy.com.au
Server: brand.tpgi.com.au
Address: 203.12.160.1

Non-authoritative answer:
Name: nova.sysygy.com.au
Address: 203.11.124.5

> 203.11.124.5
Server: brand.tpgi.com.au
Address: 203.12.160.1

*** brand.tpgi.com.au can't find 203.11.124.5: Non-existent domain
> alphaserver.scottcarver.com.au
Server: brand.tpgi.com.au
Address: 203.12.160.1

Non-authoritative answer:
Name: alphaserver.scottcarver.com.au
Address: 203.62.162.2

> 203.62.162.2
Server: brand.tpgi.com.au
Address: 203.12.160.1

*** brand.tpgi.com.au can't find 203.62.162.2: Non-existent domain

==============================================

And here's more details on the failed reverse lookup to my MS DNS :

==============================================

> set d2
> 203.11.124.5
Server: brand.tpgi.com.au
Address: 203.12.160.1

------------
SendRequest(), len 43
HEADER:
opcode = QUERY, id = 7, rcode = NOERROR
header flags: query, want recursion
questions = 1, answers = 0, authority records = 0, additional
= 0

QUESTIONS:
5.124.11.203.in-addr.arpa, type = PTR, class = IN

------------
------------
Got answer (43 bytes):
HEADER:
opcode = QUERY, id = 7, rcode = NXDOMAIN
header flags: response, auth. answer, want recursion, recursion
avail.
questions = 1, answers = 0, authority records = 0, additional
= 0

QUESTIONS:
5.124.11.203.in-addr.arpa, type = PTR, class = IN

------------
*** brand.tpgi.com.au can't find 203.11.124.5: Non-existent domain
>
==============================================

I have replicated this scenario from various Unix-based DNS systems.

So there seems to be some problem doing reverse lookups from a Unix DNS
to a MS DNS.

Any help will be much appreciated.

Ron.

------------------------------------------------------------------------
-----
Ron Bertino (MCP, B.Sc., Dip.Ed.)
Systems / Software Engineer
ron@tpgi.com.au -or- ronb@sysygy.com.au
ICQ # : 2254716 (http://wwp.mirabilis.com/2254716)
Homepage : http://www1.tpgi.com.au/users/ron/