= DNS
{{tag>linux tcpip dns}}

== related
  * [[tcpip:dns:start|]]
  * [[tcpip:dns:dnsmasq]]
  * [[tcpip:dns:bind9]]
  * [[linux:dns:127]]
  * [[https://www.dns0.eu/]]
  * [[https://one.one.one.one/]]

== direct 
  * esbrinar qui gestiona les dades de xarxa (netplan)
  * aplicar els canvis (networkmanager en desktops)

=== DNS populars
  * Cloudflare DNS (1.1.1.1, 1.0.0.1)
  * OpenDNS (208.67.222.222, 208.67.220.220)
  * Google Public DNS (8.8.8.8, 8.8.4.4)

== configuració DNS
  * interficie de xarxa:<code bash>ip a
ifconfig -a</code>

=== search
Search domain means the domain that will be automatically appended when you only use the hostname for a particular host or computer. This is basically used in a local network.

<code properties /etc/network/interfaces>dns-search xyz.com ##If you put this into /etc/network/interfaces<code>
<code properties>search xyz.com ##If you put this into /etc/resolvconf/resolv.conf.d/base|head|tail</code>

<code bash>host test
test.xyz.com has address 192.168.1.5</code>
<code bash>nslookup test
Server:     192.168.1.11
Address:    192.168.1.11#53

Name:   test.xyz.com
Address: 192.168.1.5</code>

/via: [[https://askubuntu.com/questions/584054/how-do-i-configure-the-search-domain-correctly]]
=== resolv.conf
  * ''/etc/resolv.conf'' es symlink de fichero generado dinámicamente
  * ''/etc/resolvconf/resolv.conf.d/head'' añade al principio de ''/etc/resolv.conf''
  * se gestiona a través de **systemd-resolved** -> **/etc/systemd/resolved.conf**

  * /etc/systemctl/resolved.conf
  * /etc/resolv.conf
    * no recomanat, sobreescrit per NetworkManager
    * <code>nameserver 8.8.8.8
nameserver 8.8.4.4</code>
  * /etc/hosts: <code>
78.47.249.138 wiki.fidmag.org
</code>


  * <code bash>resolvectl status</code>
  * llistat DNS: <code bash>resolvectl --list</code>
  * actualitzar canvis pendents: <code bash>resolvectl --enable-updates</code>
  * interficie responent: <code bash>resolvectl -i</code>
  * update files: <code bash>resolvectl -u</code>


=== netplan (servers)
  * identificar el netplan fet servir:<code bash>cat /etc/netplan/01-network-manager-all.yaml</code>
  * <code yaml NetworkManager>
# Let NetworkManager manage all devices on this system
network:
  version: 2
  renderer: NetworkManager 
</code>
  * <code yaml DHCP>network:
  version: 2
  ethernets:
    eth0:
      dhcp4: true
      nameservers:
        addresses: [8.8.8.8, 8.8.4.4]</code>
  * <code yaml IP-fija>network:
  version: 2
  ethernets:
    eth0:
      dhcp4: false
      addresses: [192.168.1.10/24]
      gateway4: 192.168.1.1
      nameservers:
        addresses:[208.67.222.222, 208.67.220.220]</code>
  * aplicar: <code bash>sudo netplan apply
sudo netplan generate # si problemas y repetir apply
</code>

=== NetworkManager
  * Interfície gràfica
  * després d'aplicar canvis, reiniciar o:<code bash>sudo systemctl restart NetworkManager</code>

== nmcli
  * <code bash>nmcli</code>
  * <code bash>nmcli connection show</code>
  * <code bash>nmcli device show eno1</code>  


== comandos (OLD)
  * NO: <code bash>systemctl status systemd-resolved.service</code>
  * clear DNS debian: <code bash>sudo systemd-resolve --flush-caches</code>
  * full config?: <code bash>systemd-analyze cat-config systemd/resolved.conf</code>