On Fri 18 Mar 2022 at 14:08:36 (-0500), Nicholas Geovanis wrote:
> On Thu, Mar 17, 2022, 11:57 PM David Wright wrote:
> > On Thu 17 Mar 2022 at 12:12:28 (+0000), Thomas Pircher wrote
> > >
> > > Cool. If you just type resolvectl, it will show you which information it
> > > got on each interface.
> >
> > This is machine F, where /etc/resolv.conf is a file, containing
> > 192.168.1.1 :
> >
> > $ resolvectl
> > Global
> > Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
> > resolv.conf mode: foreign
> > Current DNS Server: 192.168.1.1
> > DNS Servers: 192.168.1.1
> >
> > Link 2 (enp2s2)
> > Current Scopes: none
> > Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS
> > DNSSEC=no/unsupported
> >
> > Link 5 (wlp2s4)
> > Current Scopes: LLMNR/IPv4 LLMNR/IPv6
> > Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS
> > DNSSEC=no/unsupported
> > $ host www.google.com
> > www.google.com has address 142.250.138.105
> > www.google.com has address 142.250.138.103
> > www.google.com has address 142.250.138.106
> > www.google.com has address 142.250.138.99
> > www.google.com has address 142.250.138.104
> > www.google.com has address 142.250.138.147
> > www.google.com has IPv6 address 2607:f8b0:4000:80e::2004
> > $ host www.lionunicorn.co.uk
> > www.lionunicorn.co.uk has address 149.255.60.149
> > $
> >
> > Those responses were instantaneous. (I don't think I should expect
> > resolvectl query to work here.)
> >
> > And this is machine R, with systemd-resolved running:
> >
> > $ ls -l /etc/resolv.conf
> > lrwxrwxrwx [ … ] /etc/resolv.conf ->
> > ../run/systemd/resolve/stub-resolv.conf
> > $ resolvectl
> > Global
> > Protocols: +LLMNR +mDNS -DNSOverTLS DNSSEC=no/unsupported
> > resolv.conf mode: stub
> >
> > Link 2 (enp1s0)
> > Current Scopes: none
> > Protocols: -DefaultRoute +LLMNR -mDNS -DNSOverTLS
> > DNSSEC=no/unsupported
> >
> > Link 4 (wlan0)
> > Current Scopes: DNS LLMNR/IPv4
> > Protocols: +DefaultRoute +LLMNR -mDNS -DNSOverTLS
> > DNSSEC=no/unsupported
> > Current DNS Server: 192.168.1.1
> > DNS Servers: 192.168.1.1
> > $ host www.google.com
> > www.google.com has address 142.251.32.196
> > www.google.com has IPv6 address 2607:f8b0:4023:1002::63
> > www.google.com has IPv6 address 2607:f8b0:4023:1002::67
> > www.google.com has IPv6 address 2607:f8b0:4023:1002::93
> > www.google.com has IPv6 address 2607:f8b0:4023:1002::69
> > ;; connection timed out; no servers could be reached
> >
> > $ resolvectl query www.google.com
> > www.google.com: 2607:f8b0:4000:805::2004 -- link: wlan0
> > 142.251.46.132 -- link: wlan0
> >
>
> Your machine F seems to resolve almost entirely IPv4 addresses for that
> host.
> But your machine R resolves almost exclusively IPv6 addresses for it.
>
> Could there be an identical hostname assigned to both IPv4 and IPv6
> interfaces?
At this end? I only see:
$ ip -4 a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group
default qlen 1000
inet 127.0.0.1/8 scope host lo
valid_lft forever preferred_lft forever
4: wlan0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP
group default qlen 1000
inet 192.168.1.17/24 scope global noprefixroute wlan0
valid_lft forever preferred_lft forever
$ ip -6 a
1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 state UNKNOWN qlen 1000
inet6 ::1/128 scope host
valid_lft forever preferred_lft forever
$
and the usual autoconfigured link addresses.
In my router, IPv6 is set to disabled.
> In general you want DNS queries to resolve with less than 500msec network
> latency. Above 1500 to 1700 msec the applications start breaking and
> network timeouts are hit.
>
> Trimming the rest of your email...
>
> -- Information acquired via protocol DNS in 33.6ms.
> > -- Data is authenticated: no
> > .........
> >
> > Cheers,
> > David.
> >
Cheers,
David.
