<html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body> I would suggest creating issue at github.com/systemd/systemd repository. I have not tested it, but sounds like it should be fixed. <div class="moz-cite-prefix">On 12. 07. 23 0:39, Muggeridge, Matt wrote: </div> <blockquote type="cite" cite="mid:SJ0PR84MB2088ED51B19B2AA8290DD9F0D831A@SJ0PR84MB2088.NAMPRD84.PROD.OUTLOOK.COM"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <meta name="Generator" content="Microsoft Word 15 (filtered medium)"> <style>@font-face {font-family:"Cambria Math"; panose-1:2 4 5 3 5 4 6 3 2 4;}@font-face {font-family:Calibri; panose-1:2 15 5 2 2 2 4 3 2 4;}p.MsoNormal, li.MsoNormal, div.MsoNormal {margin:0cm; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ligatures:standardcontextual; mso-fareast-language:EN-US;}a:link, span.MsoHyperlink {mso-style-priority:99; color:#0563C1; text-decoration:underline;}p.MsoListParagraph, li.MsoListParagraph, div.MsoListParagraph {mso-style-priority:34; margin-top:0cm; margin-right:0cm; margin-bottom:0cm; margin-left:36.0pt; font-size:11.0pt; font-family:"Calibri",sans-serif; mso-ligatures:standardcontextual; mso-fareast-language:EN-US;}span.EmailStyle17 {mso-style-type:personal-compose; font-family:"Calibri",sans-serif; color:windowtext;}.MsoChpDefault {mso-style-type:export-only; font-family:"Calibri",sans-serif; mso-fareast-language:EN-US;}div.WordSection1 {page:WordSection1;}ol {margin-bottom:0cm;}ul {margin-bottom:0cm;}</style> <div class="WordSection1"> Hello there!<o:p></o:p> <o:p> </o:p> In our IPv6 network, the address of a Recursive DNS Server (RDNSS) is supplied in a Router Advertisement (RA), with a lifetime of 60 seconds.<o:p></o:p> <o:p> </o:p> It appears that RDNSS lifetime is not being honoured (<a href="https://www.rfc-editor.org/rfc/rfc8106.html#section-5.1:~:text=in the option.-,Lifetime,-32-bit unsigned" moz-do-not-send="true">RFC 8106, section 5.1</a>). I reviewed the code and can see where the <a href="https://github.com/systemd/systemd-stable/blob/4a31fa2fb040005b73253da75cf84949b8485175/src/network/networkd-ndisc.c#L712" moz-do-not-send="true">RDNSS lifetime is being saved</a>, though I was unable to determine how it was being handled upon expiry.<o:p></o:p> <o:p> </o:p> How do I configure networkd so that the RA’s RDNSS lifetime is honoured?<o:p></o:p> <o:p> </o:p> Here is a summary of the simple protocol exchange:<o:p></o:p> <o:p> </o:p> <ol style="margin-top:0cm" type="1" start="1"> <li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">Router: Send RA [RDNSS address of “nameserver60s”, lifetime: “60”]<o:p></o:p></li> <li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">Host: “resolvectl” shows the link’s DNS server now lists the RDNSS address of “nameserver60s”<o:p></o:p></li> <li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">** Wait for more than 60 seconds – the RDNSS entry should expire **<o:p></o:p></li> <li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level1 lfo1">Host:<o:p></o:p></li> <ol style="margin-top:0cm" type="a" start="1"> <li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level2 lfo1">“resolvectl” continues to list the address of “nameserver60s” on the link.<o:p></o:p></li> <li class="MsoListParagraph" style="margin-left:0cm;mso-list:l0 level2 lfo1">Using tcpdump to trace “ping test.example.com”, the “nameserver60s” is still being used. It never timed out.<o:p></o:p></li> </ol> </ol> <o:p> </o:p> Here is my network configuration, showing UseDNS and UseDomains both set to “yes”:<o:p></o:p> <o:p> </o:p> ------------------------------------------------------------<o:p></o:p> $ cat /etc/systemd/network/10-eno0.network <o:p></o:p> [Match]<o:p></o:p> KernelCommandLine=!nfsroot<o:p></o:p> Name=eno0<o:p></o:p> <o:p> </o:p> [DHCP]<o:p></o:p> ClientIdentifier=mac<o:p></o:p> RouteMetric=10<o:p></o:p> UseDomains=yes<o:p></o:p> UseHostname=yes<o:p></o:p> UseMTU=yes<o:p></o:p> <o:p> </o:p> [Network]<o:p></o:p> #DHCP=ipv6<o:p></o:p> Address=10.1.1.1/24<o:p></o:p> #DNS=1.2.3.6<o:p></o:p> Gateway=1.1.1.2<o:p></o:p> IPv6AcceptRA=yes<o:p></o:p> <o:p> </o:p> [IPv6AcceptRA]<o:p></o:p> UseDNS=yes<o:p></o:p> UseDomains=yes<o:p></o:p> ------------------------------------------------------------<o:p></o:p> <o:p> </o:p> Grateful for any suggestions.<o:p></o:p> <o:p> </o:p> Kind regards,<o:p></o:p> Matt.<o:p></o:p> PS: We’re on systemd 250. I’ve searched later versions of the <a href="https://github.com/systemd/systemd/releases" moz-do-not-send="true">release notes</a> and it seems there have been no changes in this area.<o:p></o:p> <o:p> </o:p> <o:p> </o:p> </div> </blockquote> <pre class="moz-signature" cols="72">-- Petr Menšík Software Engineer, RHEL Red Hat, <a class="moz-txt-link-freetext" href="http://www.redhat.com/">http://www.redhat.com/</a> PGP: DFCF908DB7C87E8E529925BC4931CA5B6C9FC5CB</pre> </body> </html>