BIND started replying to queries for .com with .COM
daniel.stirnimann at switch.ch
Thu Mar 31 19:58:01 UTC 2016
When BIND first introduced this Case-Insensitive Response Compression
(See https://kb.isc.org/article/AA-01113) I found out that BIND
zone_name case sensitivity in a zone statement is preferred over name
case sensitivity in the zone itself.
So, you can get a google.COM answer because the zone statement at the
authoritative com name server you were talking to is "COM.".
On 30.03.16 23:21, Mike Bernhardt wrote:
> I think you misunderstood me. I was getting back google.COM even when I
> queried the server using nslookup from a command prompt on my Windows
> desktop. The probe was failing because it is case-sensitive, but that was
> the symptom, not the problem.
> For example:
> Server: athena.bart.gov
> Address: 184.108.40.206
> Non-authoritative answer:
> Name: google.COM
> Addresses: 2607:f8b0:4005:801::200e
> Given that the problem cleared after restarting BIND on its CentOS host, I'd
> say the problem was BIND.
> -----Original Message-----
> From: Mark Andrews [mailto:marka at isc.org]
> Sent: Tuesday, March 29, 2016 5:19 PM
> To: Mike Bernhardt
> Cc: bind-users at isc.org
> Subject: Re: BIND started replying to queries for .com with .COM
> Your monitoring probe is broken.
> STD 13 says that that the DNS is case preserving. The problem is that lots
> of servers aren't case preserving instead they echo back the query case in
> the owner names of records returned which named then records.
> In message <email@example.com>, "Mike Bernhardt"
>> I rebooted one of our BIND VMs this morning. It's running BIND
>> 9.10.3-P3. We noticed that queries for domains with domain.com were
>> answered with domain.COM with the .COM in capital letters. Other
>> high-levels like .org were not changed. It caused a monitoring probe
>> to complain because it wasn't getting back what it asked for.
>> Restarting bind on this server fixed the problem. Any ideas on what
>> happened, or where to look?
>> Please visit https://lists.isc.org/mailman/listinfo/bind-users to
>> unsubscribe from this list
>> bind-users mailing list
>> bind-users at lists.isc.org
> Mark Andrews, ISC
> 1 Seymour St., Dundas Valley, NSW 2117, Australia
> PHONE: +61 2 9871 4742 INTERNET: marka at isc.org
> Please visit https://lists.isc.org/mailman/listinfo/bind-users to unsubscribe from this list
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