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Re: Slow connections - DNS problems?



On 24/03/2021 05:32, 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)

Just another point to add to what other people are saying. This line
looks a bit suspicious to me. The "search" line is _supposed_ to be a
list of domains which your computer is part of. It's implemented such
that, when the resolver is asked to look up a short name (e.g. "printer"
or "my-laptop" etc), then each item in the search list will be appended
in turn and a lookup made. So, for example you could have "search
example.com example.net" and a lookup for "gateway" would try
"gateway.example.com" then "gateway.example.net" in turn.

According to IANA, who keep the register of top level domains at
https://www.iana.org/domains/root/db, there is no such domain called
"telus", so one would expect a lookup for "gateway.telus" to fail
(unless it's a private domain, only hosted on the telus DNS servers.
That's perfectly possible).


> 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.
Do you have an IPv6 address? If you run "ip -c -6 a", do you have an
address with "scope global"? You may have one with "scope link", but
that won't help at the moment. If you do, then congratulations: Telus
have provided you with a connection to the modern internet. If not, then
you won't be able to reach these resolver addresses.
>
> I suspect there's something fishy about that home resolv.conf;
> can one of you gurus suggest what it might be?
>

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