<div dir="auto">Thanks for the input. I speculated it could be a problem related to how my router is returning some dns queries, given that's the other common piece.<div dir="auto">The Fedora laptop has systemd resolve version 246 which is way more up to date.</div><div dir="auto"><br></div><div dir="auto">What you are saying makes sense though. I reviewed the bugs and it seems to match perfectly. </div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Sat, Apr 17, 2021, 05:11 Mantas Mikulėnas <<a href="mailto:grawity@gmail.com" target="_blank" rel="noreferrer">grawity@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div dir="ltr"><div dir="ltr">On Fri, Apr 16, 2021 at 7:41 PM Francesco Belladonna <<a href="mailto:francesco@fc5.me" rel="noreferrer noreferrer" target="_blank">francesco@fc5.me</a>> wrote:<br></div><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="ltr"><div><p style="margin:0px 0px 1.2em">Greetings,<br>I’ve been trying to debug why systemd-resolve is not able to perform <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">nslookup <a href="http://static-exp1.licdn.com" rel="noreferrer noreferrer" target="_blank">static-exp1.licdn.com</a></code>.<br>Altering <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">/etc/resolv.conf</code> to point directly to the DNS server (or my router in this case) solves the problem, which seems to suggest the problem is isolated to systemd-resolve.<br>The problem is identical on both my laptops which are running 2 different O.S. (Kubuntu 18.04 and Fedora 33).<br>The entire DNS configuration is provided by the router acting as DHCP server.</p>
<p style="margin:0px 0px 1.2em">The system I’m performing my tests is Kubuntu, where the systemd version is:</p>
<pre style="font-family:Consolas,Inconsolata,Courier,monospace;font-size:1em;line-height:1.2em;margin:1.2em 0px"><code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;background-color:rgb(248,248,248);white-space:pre-wrap;overflow:auto;border-radius:3px;border:1px solid rgb(204,204,204);padding:0.5em 0.7em;display:block">systemd --version
systemd 237
+PAM +AUDIT +SELINUX +IMA +APPARMOR +SMACK +SYSVINIT +UTMP +LIBCRYPTSETUP +GCRYPT +GNUTLS +ACL +XZ +LZ4 +SECCOMP +BLKID +ELFUTILS +KMOD -IDN2 +IDN -PCRE2 default-hierarchy=hybrid
</code></pre><p style="margin:0px 0px 1.2em"><code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">SYSTEMD_LOG_LEVEL</code> is set to <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">debug</code>.<br>Is there any other useful tool I can use to debug this further?<br>The problematic domain is <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline"><a href="http://static-exp1.licdn.com" rel="noreferrer noreferrer" target="_blank">static-exp1.licdn.com</a></code> which is the CDN for LinkedIn. I have no idea why <em>this</em> specific domain is affected.</p></div></div></blockquote><div>Most likely because it has one of those <i>interesting</i> CNAME chains:</div><div><br></div><div><font face="monospace">$ rdt <a href="http://static-exp1.licdn.com" rel="noreferrer noreferrer" target="_blank">static-exp1.licdn.com</a><br><a href="http://static-exp1.licdn.com" rel="noreferrer noreferrer" target="_blank">static-exp1.licdn.com</a> = <a href="http://2-01-2c3e-003d.cdx.cedexis.net" rel="noreferrer noreferrer" target="_blank">2-01-2c3e-003d.cdx.cedexis.net</a><br> <a href="http://2-01-2c3e-003d.cdx.cedexis.net" rel="noreferrer noreferrer" target="_blank">2-01-2c3e-003d.cdx.cedexis.net</a> = <a href="http://li-prod-static.azureedge.net" rel="noreferrer noreferrer" target="_blank">li-prod-static.azureedge.net</a><br> <a href="http://li-prod-static.azureedge.net" rel="noreferrer noreferrer" target="_blank">li-prod-static.azureedge.net</a> = <a href="http://li-prod-static.afd.azureedge.net" rel="noreferrer noreferrer" target="_blank">li-prod-static.afd.azureedge.net</a><br> <a href="http://li-prod-static.afd.azureedge.net" rel="noreferrer noreferrer" target="_blank">li-prod-static.afd.azureedge.net</a> = <a href="http://star-azureedge-prod.trafficmanager.net" rel="noreferrer noreferrer" target="_blank">star-azureedge-prod.trafficmanager.net</a><br> <a href="http://star-azureedge-prod.trafficmanager.net" rel="noreferrer noreferrer" target="_blank">star-azureedge-prod.trafficmanager.net</a> = <a href="http://dual.t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">dual.t-0009.t-msedge.net</a><br> <a href="http://dual.t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">dual.t-0009.t-msedge.net</a> = <a href="http://t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">t-0009.t-msedge.net</a><br> <a href="http://t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">t-0009.t-msedge.net</a> = <a href="http://Edge-Prod-LON21r3.ctrl.t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">Edge-Prod-LON21r3.ctrl.t-0009.t-msedge.net</a><br> <a href="http://edge-prod-lon21r3.ctrl.t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">edge-prod-lon21r3.ctrl.t-0009.t-msedge.net</a> = <a href="http://standard.t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">standard.t-0009.t-msedge.net</a><br> <a href="http://standard.t-0009.t-msedge.net" rel="noreferrer noreferrer" target="_blank">standard.t-0009.t-msedge.net</a> = 13.107.213.19, 13.107.246.19, 2620:1ec:46::19, 2620:1ec:bdf::19</font><br></div><div><br></div><div>(Though sometimes it's shorter, pointing at epsiloncdn instead of Azure. It depends on where you're making the query from.)</div><div><br></div><div>I <i>think</i> this was fixed in git a few weeks ago. There's already an Ubuntu bug report for the same issue: <a href="https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1921636" rel="noreferrer noreferrer" target="_blank">https://bugs.launchpad.net/ubuntu/+source/systemd/+bug/1921636</a></div></div><div><br></div>-- <br><div dir="ltr"><div dir="ltr">Mantas Mikulėnas</div></div></div>
</blockquote></div>