1.. zephyr:code-sample:: dns-resolve
2   :name: DNS resolve
3   :relevant-api: dns_resolve net_mgmt
4
5   Resolve an IP address for a given hostname.
6
7Overview
8********
9
10This application will setup IP address for the device, and then
11try to resolve various hostnames according to how the user has
12configured the system.
13
14- If IPv4 is enabled, then A record for ``www.zephyrproject.org`` is
15  resolved.
16- If IPv6 is enabled, then AAAA record for ``www.zephyrproject.org`` is
17  resolved.
18- If mDNS is enabled, then ``zephyr.local`` name is resolved.
19
20Requirements
21************
22
23- :ref:`networking_with_host`
24
25- screen terminal emulator or equivalent.
26
27- For most boards without ethernet, the ENC28J60 Ethernet module is required.
28
29- dnsmasq application. The dnsmasq version used in this sample is:
30
31.. code-block:: console
32
33    dnsmasq -v
34    Dnsmasq version 2.76  Copyright (c) 2000-2016 Simon Kelley
35
36Building and Running
37********************
38
39Network Configuration
40=====================
41
42Open the project configuration file for your platform, for example:
43:file:`prj_frdm_k64f.conf` is the configuration file for the
44:zephyr:board:`frdm_k64f` board.
45
46In this sample application, both static or DHCPv4 IP addresses are supported.
47Static IP addresses are specified in the project configuration file,
48for example:
49
50.. code-block:: cfg
51
52	CONFIG_NET_CONFIG_MY_IPV6_ADDR="2001:db8::1"
53	CONFIG_NET_CONFIG_PEER_IPV6_ADDR="2001:db8::2"
54
55are the IPv6 addresses for the DNS client running Zephyr and the DNS server,
56respectively.
57
58DNS server
59==========
60
61The dnsmasq tool may be used for testing purposes. On a Zephyr project default
62installation, the sample dnsmasq start script can be found in the `net-tools`_
63project or downloaded from https://github.com/zephyrproject-rtos/net-tools.
64
65Open a terminal window and type:
66
67.. code-block:: console
68
69    $ cd net-tools
70    $ sudo ./dnsmasq.sh
71
72The default project configurations settings for this sample uses the public
73Google DNS servers.  In order to use the local dnsmasq server, please edit
74the appropriate 'prj.conf' file and update the DNS server addresses.  For
75instance, if using the usual IP addresses assigned to testing, update them
76to the following values:
77
78.. code-block:: cfg
79
80    CONFIG_DNS_SERVER1="192.0.2.2:5353"
81    CONFIG_DNS_SERVER2="[2001:db8::2]:5353"
82
83.. note::
84    DNS uses port 53 by default, but the dnsmasq.conf file provided by
85    net-tools uses port 5353 to allow executing the daemon without
86    superuser privileges.
87
88If dnsmasq fails to start with an error like this:
89
90.. code-block:: console
91
92    dnsmasq: failed to create listening socket for port 5353: Address already in use
93
94Open a terminal window and type:
95
96.. code-block:: console
97
98    $ killall -s KILL dnsmasq
99
100Try to launch the dnsmasq application again.
101
102For testing mDNS, use Avahi script in net-tools project:
103
104.. code-block:: console
105
106    $ cd net-tools
107    $ ./avahi-daemon.sh
108
109.. _`net-tools`: https://github.com/zephyrproject-rtos/net-tools
110
111LLMNR Responder
112===============
113
114If you want Zephyr to respond to a LLMNR DNS request that Windows host is
115sending, then following config options could be set:
116
117.. code-block:: cfg
118
119    CONFIG_NET_HOSTNAME_ENABLE=y
120    CONFIG_NET_HOSTNAME="zephyr-device"
121    CONFIG_DNS_RESOLVER=y
122    CONFIG_LLMNR_RESPONDER=y
123
124A Zephyr host needs a hostname assigned to it so that it can respond to a DNS
125query. Note that the hostname should not have any dots in it.
126
127
128QEMU x86
129========
130
131To use QEMU for testing, follow the :ref:`networking_with_qemu` guide.
132
133
134FRDM K64F
135=========
136
137Open a terminal window and type:
138
139.. zephyr-app-commands::
140   :zephyr-app: samples/net/dns_resolve
141   :board: frdm_k64f
142   :goals: build flash
143   :compact:
144
145See :zephyr:board:`Freedom-K64F board documentation <frdm_k64f>` for more information
146about this board.
147
148Open a terminal window and type:
149
150.. code-block:: console
151
152    $ screen /dev/ttyACM0 115200
153
154
155Use 'dmesg' to find the right USB device.
156
157Once the binary is loaded into the FRDM board, press the RESET button.
158
159Wi-Fi
160=====
161
162The IPv4 Wi-Fi support can be enabled in the sample with
163:ref:`Wi-Fi snippet <snippet-wifi-ipv4>`.
164