<div dir="ltr">Hi Veronique.<div>As Petr said, please don't send a pcap. This is getting beyond the scope of the list and into proper support territory. For which I would recommend that CERN pay ISC for professional support services.</div><div><br></div><div>Regarding your external example, I get this:</div><div>%dig @<a href="http://192.65.187.5" target="_blank">192.65.187.5</a> <a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a> | grep flags | grep ANSWER<br></div><div>;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1<br></div><div><br></div><div><a href="http://ip-dns-0.cern.ch">ip-dns-0.cern.ch</a>. 900 IN A 137.138.28.176<br></div><div>; <<>> DiG 9.18.5 <<>> @<a href="http://137.138.28.176">137.138.28.176</a> <a href="http://foundservices.cern.ch">foundservices.cern.ch</a><br>; (1 server found)<br>;; global options: +cmd<br>;; connection timed out; no servers could be reached<br></div><div><br></div><div>Both queries and responses are different from the ones in your mails and the response I receive for "<a href="http://foundservices.cern.ch">foundservices.cern.ch</a>" from ext-dns-1 contains only 1 answer, regardless of whether recursion (which the server doesn't accept) is requested or not.</div><div><br></div><div>In short, this example does not help to explain what you are seeing.</div><div>Greg</div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Thu, 27 Oct 2022 at 13:28, Veronique Lefebure <<a href="mailto:veronique.lefebure@cern.ch" target="_blank">veronique.lefebure@cern.ch</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><u></u>
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Well,
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So here a bit more details.
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Sorry, I cannot take an example with a DNS server accessible to you (*) because they have all been upgraded to 9.16.
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The .<a href="http://cern.ch" target="_blank">cern.ch</a> contains:
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<div>
<span style="font-family:"courier new",courier">spectrum-lb IN NS <a href="http://ip-dns-1.cern.ch" target="_blank">ip-dns-1.cern.ch</a>.</span>
<br><span style="font-family:"courier new",courier">spectrum-lb IN NS <a href="http://ip-dns-2.cern.ch" target="_blank">ip-dns-2.cern.ch</a>.</span>
<br><span style="font-family:"courier new",courier">spectrum IN CNAME <a href="http://spectrum-lb.cern.ch" target="_blank">spectrum-lb.cern.ch</a>.</span>
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<br>
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and
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<div>
<a href="http://spectrum-lb.cern.ch" target="_blank">spectrum-lb.cern.ch</a> contains:
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<br><span style="font-family:"courier new",courier">$ORIGIN .</span>
<br><span style="font-family:"courier new",courier">$TTL 60 ; 1 minute</span>
<br><span style="font-family:"courier new",courier"><a href="http://spectrum-lb.cern.ch" target="_blank">spectrum-lb.cern.ch</a> IN SOA <a href="http://ip-dns-1.cern.ch" target="_blank">ip-dns-1.cern.ch</a>. <a href="http://internal-dns.cern.ch" target="_blank">internal-dns.cern.ch</a>. (</span>
<br><span style="font-family:"courier new",courier">273 ; serial</span>
<br><span style="font-family:"courier new",courier">3600 ; refresh (1 hour)</span>
<br><span style="font-family:"courier new",courier">300 ; retry (5 minutes)</span>
<br><span style="font-family:"courier new",courier">3600000 ; expire (5 weeks 6 days 16 hours)</span>
<br><span style="font-family:"courier new",courier">60 ; minimum (1 minute)</span>
<br><span style="font-family:"courier new",courier">)</span>
<br><span style="font-family:"courier new",courier">NS <a href="http://ip-dns-1.cern.ch" target="_blank">ip-dns-1.cern.ch</a>.</span>
<br><span style="font-family:"courier new",courier">NS <a href="http://ip-dns-2.cern.ch" target="_blank">ip-dns-2.cern.ch</a>.</span>
<br><span style="font-family:"courier new",courier">A xxx.xxx.xx.140</span>
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<div>
named configuration file is identical between 9.11 and 9.16 except for the following options that we have added for 9.16:
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<span style="font-family:"courier new",courier"> #BIND916 options</span>
<br><span style="font-family:"courier new",courier">qname-minimization disabled;</span>
<br><span style="font-family:"courier new",courier">stale-answer-enable no;</span>
<br><span style="font-family:"courier new",courier">stale-refresh-time 0; #default is 30</span>
<br><span style="font-family:"courier new",courier">max-stale-ttl 1w;</span>
<br><span style="font-family:"courier new",courier">dnssec-policy none;</span>
<br><span style="font-family:"courier new",courier">synth-from-dnssec no;</span>
<br><span style="font-family:"courier new",courier">min-cache-ttl 0;</span>
<br><span style="font-family:"courier new",courier">min-ncache-ttl 0;</span>
<br><span style="font-family:"courier new",courier">minimal-responses no;</span>
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<div>
(*) On an external DNS server you can try with the following similar case:
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<br>
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<div>
Running DiG 9.11.21 on a linux client
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<div>
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<div>
ext-dns-1 (<span style="font-family:"courier new",courier">192.65.187.5) </span>runs BIND9.16:
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<div>
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<div>
<span style="font-family:"courier new",courier">dig @ext-dns-1 <a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a> | grep flags | grep ANSWER</span>
<br><span style="font-family:"courier new",courier">;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1</span>
<br>
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<div>
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<div>
<span style="font-family:"courier new",courier">dig @ext-dns-1 <a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a> <strong>+norecurse</strong> | grep flags | grep ANSWER</span>
<br><span style="font-family:"courier new",courier">;; flags: qr aa ra; QUERY: 1, ANSWER: <span style="color:rgb(255,0,0)"><strong>1</strong></span>, AUTHORITY: 0, ADDITIONAL: 1</span>
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</div>
<div>
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<div>
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<div>
<span style="font-family:arial,helvetica,sans-serif">Full output:</span>
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<div>
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<span style="font-family:"courier new",courier">dig @<a href="http://192.65.187.5" target="_blank">192.65.187.5</a> <a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a> +norecurse</span>
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<div>
<span style="font-family:"courier new",courier">; <<>> DiG 9.11.21 <<>> @<a href="http://192.65.187.5" target="_blank">192.65.187.5</a> <a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a> +norecurse</span>
<br><span style="font-family:"courier new",courier">; (1 server found)</span>
<br><span style="font-family:"courier new",courier">;; global options: +cmd</span>
<br><span style="font-family:"courier new",courier">;; Got answer:</span>
<br><span style="font-family:"courier new",courier">;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 9899</span>
<br><span style="font-family:"courier new",courier">;; flags: qr aa ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1</span>
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<div>
<span style="font-family:"courier new",courier">;; OPT PSEUDOSECTION:</span>
<br><span style="font-family:"courier new",courier">; EDNS: version: 0, flags:; udp: 1232</span>
<br><span style="font-family:"courier new",courier">; COOKIE: 8786b980a1a80a7901000000635a7898a512a21aa6138faf (good)</span>
<br><span style="font-family:"courier new",courier">;; QUESTION SECTION:</span>
<br><span style="font-family:"courier new",courier">;<a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a>. IN A</span>
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<div>
<span style="font-family:"courier new",courier">;; ANSWER SECTION:</span>
<br><span style="font-family:"courier new",courier"><a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a>. 900 IN CNAME <a href="http://db-lb-1234.cern.ch" target="_blank">db-lb-1234.cern.ch</a>.</span>
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<div>
<span style="font-family:"courier new",courier">;; Query time: 2 msec</span>
<br><span style="font-family:"courier new",courier">;; SERVER: 192.65.187.5#53(192.65.187.5)</span>
<br><span style="font-family:"courier new",courier">;; WHEN: Thu Oct 27 14:24:56 CEST 2022</span>
<br><span style="font-family:"courier new",courier">;; MSG SIZE rcvd: 103</span>
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<div>
ip-dns-0 runs BIND9.11:
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<span style="font-family:"courier new",courier">dig @ip-dns-0 <a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a> | grep flags | grep ANSWER</span>
<br><span style="font-family:"courier new",courier">;; flags: qr aa rd; QUERY: 1, ANSWER: 2, AUTHORITY: 2, ADDITIONAL: 4</span>
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<div>
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<div>
<span style="font-family:"courier new",courier">dig @ip-dns-0 <a href="http://foundservices.cern.ch" target="_blank">foundservices.cern.ch</a> <strong>+norecurse</strong> | grep flags | grep ANSWER</span>
<br><span style="font-family:"courier new",courier">;; flags: qr aa; QUERY: 1, ANSWER:<span style="color:rgb(255,0,0)"> <strong>2</strong></span>, AUTHORITY: 2, ADDITIONAL: 4</span>
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</div>
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<div>
<br>
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<br>
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<div>
Does that help ?
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<div>
<br>
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<div>
Greg, can I send you a pcap file in a private email ?
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<br>
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<br>
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<div>
Thanks,
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<div>
Veronique
</div>
<blockquote type="cite">
<div>
On 27/10/2022 10:09 Greg Choules <<a href="mailto:gregchoules%2Bbindusers@googlemail.com" target="_blank">gregchoules+bindusers@googlemail.com</a>> wrote:
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<br>
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<div dir="ltr">
Hi Veronique.
<div>
No, we cannot easily reproduce this behaviour because we have no knowledge of the configs of either of those servers, the details of the zones you have configured, the contents of those zones or of the system on which you are running the dig command.
<br>
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<br>
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<div>
As I said, we need to see everything please:
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<div>
- Full digs, not <a id="m_-7096964283847494353m_8463298922022168608m_8989769194844281937plusReplyChip-1" class="gmail_plusreply"></a>+short
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<div>
- you have specified @ip-dns0 and @ip-dns1 - the full configs of both of those servers please, including zone definitions and contents for where "<a href="http://spectrum.cern.ch/" rel="noopener" target="_blank">spectrum.cern.ch</a>" lives as it is not a name that can be resolved from the public Internet
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<div>
- a binary pcap file, using the -w option of tcpdump, capturing all port 53 traffic (UDP and TCP) between this machine and both DNS servers.
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<div>
<br>
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<div>
By the way, when using the <a id="m_-7096964283847494353m_8463298922022168608plusReplyChip-4" class="gmail_plusreply"></a>@<server> option of dig please use explicit IP addresses, not names. If you use a name, then dig first has to resolve that name and the place it will go to do that is resolv.conf. So it is now dependent on your system DNS setup to get an IP address to send the dig to.
</div>
<div>
Also, you have specified @<simple_host_name> not @<FQDN>. This suggests to me that in resolv.conf you have a 'search' list. Personally I don't like search lists because they potentially increase the workload of the DNS system generally, lengthen query times and mean that you can't be sure exactly where an answer came from.
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<br>
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<div>
Thanks, Greg
<br><a class="gmail_plusreply"><br></a>
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<br>
<div class="gmail_quote">
<div class="gmail_attr" dir="ltr">
On Thu, 27 Oct 2022 at 08:08, Veronique Lefebure <<a href="mailto:veronique.lefebure@cern.ch" rel="noopener" target="_blank">veronique.lefebure@cern.ch</a>> wrote:
<br>
</div>
<blockquote>
<u></u>
<div>
<div>
Hi all,
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<div>
<br>
</div>
<div>
yes, here is a concrete example:
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# ip-dns-1 runs BIND 9.16.33:
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<br>
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dig @ip-dns-1 <a href="http://spectrum.cern.ch" rel="noopener" target="_blank">spectrum.cern.ch</a> +short +norecurse
<br><a href="http://spectrum-lb.cern.ch" rel="noopener" target="_blank">spectrum-lb.cern.ch</a>. <------------- Here we get only the CNAME
<br>
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<br>
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<div>
# ip-dns-0 runs BIND 9.11:
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<div>
<br>
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<div>
dig @ip-dns-0 <a href="http://spectrum.cern.ch" rel="noopener" target="_blank">spectrum.cern.ch</a> +short +norecurse
<br><a href="http://spectrum-lb.cern.ch" rel="noopener" target="_blank">spectrum-lb.cern.ch</a>.
<br>xxx.xxx.xx.140 <-------- Here we get in addition the IP of <a href="http://spectrum-lb.cern.ch" rel="noopener" target="_blank">spectrum-lb.cern.ch</a>.
<br>
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<div>
<br>
</div>
<div>
<br>
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<div>
And yes, a capture shows confirms indeed that dig returns less information when the BIND 9.16.33 DNS server is used.
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<br>
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<div>
I guess you can easily reproduce that behaviour, unless it is due to a mis-configuration bit on our DNS server ?
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<br>
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<div>
Thanks,
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<div>
Véronique
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<div>
<br>
</div>
<blockquote type="cite">
<div>
On 26/10/2022 21:04 Greg Choules <<a href="mailto:gregchoules%2Bbindusers@googlemail.com" rel="noopener" target="_blank">gregchoules+bindusers@googlemail.com</a>> wrote:
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<br>
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<br>
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<div dir="ltr">
Hi Veronique.
<div>
As other people have said, more details please.
</div>
<div>
<br>
</div>
<div>
To have a complete picture of what is going on, not only would we need to know what your dig tests look like, but also where dig is sending its queries and how that DNS server is configured.
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<br>
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<div>
You can tell dig to send queries anywhere, using @<server>. However, if you don't use that it will default to using the nameservers in /etc/resolv.conf. So it may be useful to see the contents of that.
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<br>
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<div>
Wherever dig is sending its queries, we would need to know what that server will do with them. So its configuration would also be useful.
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<br>
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<div>
Lastly, the best way to see queries and responses, right down to the nuts and bolts, is with a packet capture.
<br>
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<br>
</div>
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<div>
You thought this was an easy question, huh ;)
</div>
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<br>
</div>Can you provide at least some of these things, to get started?
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<br>
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<div>
Cheers, Greg
</div>
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<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">
On Wed, 26 Oct 2022 at 16:41, Veronique Lefebure <<a href="mailto:veronique.lefebure@cern.ch" rel="noopener" target="_blank">veronique.lefebure@cern.ch</a>> wrote:
<br>
</div>
<blockquote>
<u></u>
<div>
<div>
Hi,
</div>
<div>
<br>
</div>
<div>
dig answer is different between BIND 9.11 and BIND 9.16(.33) when +norecurse option is used.
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<div>
Is this documented somewhere ?
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<br>
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<div>
Is there an option that needs to be set so that the behaviour of 9.16 is the same as the one in 9.11.
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The change is that with 9.16, if the requested name is a CNAME, only the CNAME value is returned by dig, while with 9.11 dig would return both the CNAME value and the IP of the CNAME.
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<br>
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<div>
Thanks,
</div>
<div>
Veronique
</div>
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