Migrate new file structure to crux (#435)

* order workflows and add submodule

* rename gitmodules file

* delete docs/.gitignore

* add vyos custom linter

* correct __pycache__ in gitignore

* add test-coverage.py

* move draw.io folder

* arrange changelog, install history and about

* arrange: firewall

* arrange: highavailability

* arrange: loadbalancing

* arrange: nat

* arrange: services

* sort configexamples and configuration interfaces

* wireles: rename wireless

* rearrange: Protocols and Policy

* rearrange: Firewall and Zone Policy

* rearrange: Interfaces

* rearrange: Interfaces

* rearrange: dynamic DNS

* hostinfo: add page to index

* rearrange: appendix

* venv: add Pipfile

* rearrange: contributing

* index: remove debugging

* rearrange: fix all figure and refs

* rearrange: commandtree

* fix: cli, openvpn, install headline level

* protocols: change headline

* firewall: move mss clamping

* ip: separate ipv4 and ipv6

* arp: move to static page

* igmp: rename multicast page

* Update to year 2021

1 files changed, 68 insertions, 0 deletions

diff --git a/docs/configuration/system/name-server.rst b/docs/configuration/system/name-server.rst
new file mode 100644
index 00000000..70848f6d
--- /dev/null
+++ b/docs/configuration/system/name-server.rst
@@ -0,0 +1,68 @@
+.. _system-dns:
+
+##########
+System DNS
+##########
+
+
+This section describes configuring DNS on the system, namely:
+
+ * DNS name servers
+ * Domain search order
+
+
+DNS name servers
+================
+
+.. cfgcmd:: set system name-server <address>
+
+   Use this command to specify a DNS server for the system to be used
+   for DNS lookups. More than one DNS server can be added, configuring
+   one at a time. Both IPv4 and IPv6 addresses are supported.
+
+
+
+Example
+-------
+
+In this example, some *OpenNIC* servers are used, two IPv4 addresses
+and two IPv6 addresses:
+
+
+.. code-block:: none
+
+   set system name-server 176.9.37.132
+   set system name-server 195.10.195.195
+   set system name-server 2a01:4f8:161:3441::1
+   set system name-server 2a00:f826:8:2::195
+
+
+Domain search order
+===================
+
+In order for the system to use and complete unqualified host names, a
+list can be defined which will be used for domain searches.
+
+
+.. cfgcmd:: set system domain-search domain <domain>
+
+   Use this command to define domains, one at a time, so that the system
+   uses them to complete unqualified host names. Maximum: 6 entries.
+
+
+.. note:: Domain names can include letters, numbers, hyphens and periods
+   with a maximum length of 253 characters.
+
+
+Example
+-------
+
+The system is configured to attempt domain completion in the following
+order: vyos.io (first), vyos.net (second) and vyos.network (last):
+
+
+.. code-block:: none
+
+   set system domain-search domain vyos.io
+   set system domain-search domain vyos.net
+   set system domain-search domain vyos.network