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Let's talk about hostname
resolution a little bit more.

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So hostname resolution allows host names to be
matched to IP addresses and the other way around.

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And the local etc host file is
the primary solution as we have just seen.

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But you will normally also
use domain name system and

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these DNS name servers
are configured in etcresolve configuration.

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That's a
classical way.

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And in this classical way you would
use the etcnsswitch conf to identify the

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order. But there's a new kid
in town and that is systemd resolved.

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Systemdresolved is how it works on
Ubuntu. Let's talk about systemd Resolved.

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It's a component of systemd and it's responsible
for managing DNS name resolution. And it runs as

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a service that communicates with the network stack
and it makes sure that multiple DNS sources can

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be used and DNS DNS records are cached
as well. So it functions as a local DNS

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server. To speed up your networking, you can
check the current status of it using systemctl status

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on systemd resolve d and you can use
resolvectl status for information about current DNS configuration.

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And if ever you need to overwrite
the DNS configuration, you edit the file etc.

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Systemdresolved configuration and restart systemd resolve D.
Let's check out the systemd resolve D.

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Okay, so what
happens when I use

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sudo systemctl status
on systemd resolve d?

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Well, oh no, I can see that systemdresolve
d could not be found. This is one

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of these parts where the distributions are taking
a different road. So I'm going to open

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a new terminal, and in my new
terminal I'm going to SSH to Ubuntu.

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And on the
Ubuntu system I'm using

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sudo systemctl status
of systemd resolve d.

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And there we can see
that systemd resolve d is running.

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So how exactly does it work?
Well, we have the input file

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etc systemd resolved conf and in
etcsystemdresolved conf you will find the

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configuration. Oh no, I don't
have vim on Ubuntu. Help.

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Let's do a quick sudo apt install
vim because really, vim is my favorite editor.

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Try again. Here we can see what the systemd resolve
d looks like. Oh boy, that's a lot of configuration.

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If ever you need to put in
some additional configuration for DNS, you can put

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it right here. Probably the most important
thing for you to do is resolvectl status.

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That will show you the current
DNS configuration on link 2 we

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can see that the current DNS
server is set to 192.21682 9.2.

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That's the local host internal DNS
that is provided by systemdresolve D and

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it allows me to cache records
which will nicely speed up my connections.