On Fri 25 Mar 2022 at 07:59:15 (+0800), Jeremy Ardley wrote: > On 25/3/22 7:26 am, Greg Wooledge wrote: > > On Fri, Mar 25, 2022 at 06:51:55AM +0800, Jeremy Ardley wrote: > > > I've been having continual problems with postfix and errors in the mail > > > log about unresolved MX and A records. Not all the time but often > > > enough to be annoying. I discovered postfix was using the > > > systemd.resolved server for DNS.
It was consistently AAAA records causing the holdup in my log: https://lists.debian.org/debian-user/2022/03/msg00656.html > > > I did some experiments with resolvectl and there were serious delays > > > looking up sites or just plain failures. In comparison my bind9 instance > > > never had a problem and returned instantly. ( systemd.resolved used the > > > same forwarders as my bind9 ) The same here. The delay was often /after/ the lookup had succeeded, but meant that you didn't get back to the prompt until a timeout expired. (I was comparing with resolvconf.) > > > Is there any compelling reason to use systemd.resolved over ordinary DNS ? > > > If not, why was it inflicted on debian? > > It's disabled by default. It's there if you wish to try it, but out of > > the box, it does absolutely nothing except sit there taking up space. > > Are you sure it's disabled by default? I don't recall converting over > to it on my various machines. And when I search on it there are lots > of pages about how to disable it, and virtually none on how to enable > it. > > I thought there might be some voodoo reason to do with something > called dbus - of which I know nothing, nor the obscure journald. The same thread as above comments on the surprise prevention of renaming the wireless interface caused by merely installing iwd: https://lists.debian.org/debian-user/2022/03/msg00727.html If you then go ahead and configure it, the default resolver is set to systemd-resolved. If you don't create the symlink necessary for that to work, /etc/resolv.conf remains empty. So there do appear to be some gotchas in play nowadays. > Anyway, bind9 works pretty well as a local caching nameserver I'm sticking with resolvconf for the time being. Cheers, David.
