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Re: Slow connections - DNS problems?



On 3/23/21 10:32 PM, Charlie Gibbs wrote:
I read Usenet (including this mailing list via the newsgroup
linux.debian.user) on my laptop. so I can keep up from anywhere.
It works well, but at home it takes 20 or 30 seconds to connect
to my NNTP server, newsguy.com.  If I take my laptop to the office
and run slrnpull there, it connects instantly.  I've mentioned this
to people in the past, and the consensus seems to be that it's some
sort of DNS problem.

My laptop is running NetworkManager.  When I wake it up at
a new location, resolv.conf (which is actually a link to
/run/NetworkManager/resolv.conf) gets overwritten with
information that works where I now am.  At the office,
it's simply:

# Generated by NetworkManager
nameserver 192.168.1.5
nameserver 192.168.1.1

while at home it becomes more intricate:

# Generated by NetworkManager
search telus
nameserver 192.168.0.1
nameserver 75.153.171.122
nameserver 2001:568:ff09:10a::56
# NOTE: the libc resolver may not support more than 3 nameservers.
# The nameservers listed below may not be recognized.
nameserver 2001:568:ff09:10b::122

My home router (supplied by Telus, notice the "search" line)
shows two DNS addresses - 75.153.176.1 and 75.153.171.122 -
on its configuration screen.  The second address (but not the
first) winds up in resolv.conf.  The router is at 192.168.0.1.
Dunno about those IPv6 addresses; I've made no conscious effort
to use IPv6 anywhere.

I suspect there's something fishy about that home resolv.conf;
can one of you gurus suggest what it might be?

Please run the following commands when your computer is connected to a given network:

$ cat /etc/debian_version

$ uname -a

$ nmcli g status

$ nmcli c show

$ nmcli d show

$ time host -v -t A www.debian.org 208.67.222.222

$ nmcli d show | perl -ae 'print $F[1],"\n" if $F[0] =~ /IP\d\.DNS\[\d+\]/' | xargs -n 1 host -v -t A www.debian.org


The second to last command uses opendns.org's primary DNS server. The last command uses whatever DNS servers Network Manager is currently using.


David


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