Re: [DNS] BIND Delegation Only

Re: [DNS] BIND Delegation Only

From: David Keegel <djk§cybersource.com.au>
Date: Fri, 21 Nov 2003 06:47:56 +1100 (EST)
] Hi Anand,
] 
] I should have provided a clearer explanation. :)

And as Alwyn said, its really a gTLD issue more than a .au issue.
 
] Bind running in delegation-only mode will not resolve addresses where the
] name servers for the domain in question are (ultimately) all in another TLD
] and where the prime TLD registry does not support glue for nameservers in
] another TLD.

This "delegation-only" mode feature was a patch added to BIND 9 shortly
after Verisign put a wildcard *.com and *.net pointing at its SiteFinder
web site.  The intended effect is to ignore wildcards.  To run BIND in
"delegation-only" mode, you need to patch the software, and change your
BIND configuration file to say what zones you want to be "delegation-only"
(eg: "com" and "net").

I thought the need to support "delegation-only" configs was much reduced
when Verisign suspended the wildcards *.com and *.net on October 4.  Of
course the wildcards could come back, but since there are currently no
wildcards in *.com and *.net, I see no reason to configure com and net
as delegation-only at this time, except maybe to test for unintended
consequences of delegation-only.

In the case of rescuegroup, it looks to me like the reason for the failure
is that there are no NS records for rescuegroup.com (a.gtld-servers.net
still returns NXDOMAIN on rescuegroup.com), therefore delegation-only
mode (if configured for "com") should say that ns1.rescuegroup.com and
ns2.rescuegroup.com are non-existent addresses.  (Bear in mind that BIND
can't distinguish between glue and synthesised records from a wildcard.)

If this is a problem, I have two suggestions:
(1) Configure BIND not to be delegation-only for com
(2) Advise rescuegroup that they have a questionable configuration.
  
On (2), they seem to use rescuegroup.com, but the gTLD servers do not
have any NS records for rescuegroup.com, which is probably because
their gTLD registrar (Network Solutions) lists rescuegroup.com as 
expired on 01-Nov-2003.

Rescue Group should renew rescuegroup.com or stop using it (eg:
change the DNS servers for rescuegroup.com.au so they don't refer
to rescuegroup.com).  Otherwise sooner or later the glue for the
expired rescuegroup.com will go away, and then rescuegroup.com.au
and afgonline.com.au will stop working for everyone (not just
those who use delegation-only mode on .com).

] In my example afgonline.com.au nameservers are in .au (rescuegroup.com.au),
] but the nameservers for rescuegroup.com.au are in .com (rescuegroup.com) and
] resolution fails at that point - no glue.
] 
] To ensure reliablility under the world according to delegation-only you need
] at least one nameserver completely within the same TLD or you become
] invisible to people who disagree with Verisign.
] 
] This is not specific to .au and is not finger pointing, simply an
] observation.
] 
] alwyn
] 
] ----- Original Message ----- 
] From: "Anand Kumria" <wildfire&#167;progsoc.uts.edu.au>
] To: <dns&#167;lists.auda.org.au>
] Sent: Thursday, November 20, 2003 2:44 PM
] Subject: Re: [DNS] BIND Delegation Only
] 
] 
] Hi Alwyn,
] 
] I'm coming a bit late here and it would seem you've since resolved your
] problem. However I'm not sure I understand what the original problem
] was, could you elaborate futher?
] 
] On Wed, Nov 12, 2003 at 04:55:55PM +1000, Alwyn Smith wrote:
] > This one had me going for a while because the problem was further up the
] dns
] > chain than I was looking.  Hopefully this info may help someone else with
] > "inexplicable" dns failures on .au domains.
] >
] > afgonline.com.au would not resolve:
] >
] > afgonline.com.au.       2554    IN      NS      ns1.rescuegroup.com.au.
] > afgonline.com.au.       2554    IN      NS      ns2.rescuegroup.com.au.
] 
] so, dig ns1.recusgroup.com.au and dig ns1.recusgroup.com.au would both
] fail?
] 
] >
] > ns1.rescuegroup.com.au. 2554    IN      A       203.103.84.232
] > ns2.rescuegroup.com.au. 2554    IN      A       210.11.148.5
] 
] Were these glue records for ausregistry.net or were they listed as NS in
] the zone file?
] 
] >
] > rescuegroup.com.au.     2477    IN      NS      ns1.rescuegroup.com.
] > rescuegroup.com.au.     2477    IN      NS      ns2.rescuegroup.com.
] 
] Same question as above.
] 
] >
] > If you operate bind in "delegation only" mode then lookups of .au domains
] > with name servers _ultimately_ in "delegation only" domains will fail.
] 
] So this is a client problem (i.e. the admin of a zone has setup
] delegation only) and there isn't much that a third party zone operator
] can do about things?
] 
] Not sure I fully understand, and insight would be appreciated.
] 
] Regards,
] Anand
] 
] -- 
]  `` We are shaped by our thoughts, we become what we think.
]  When the mind is pure, joy follows like a shadow that never
]  leaves. '' -- Buddha, The Dhammapada
] 
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___________________________________________________________________________
 David Keegel <djk&#167;cybersource.com.au>  http://www.cyber.com.au/users/djk/
 Cybersource P/L: Linux/Unix Systems Administration Consulting/Contracting
Received on Fri Oct 03 2003 - 00:00:00 UTC

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