1.. highlight:: none
2.. _Requirements:
3
4************
5Requirements
6************
7
8Hardware
9========
10
11Knot DNS requirements are not very demanding for typical
12installations, and a commodity server or a virtual solution will be
13sufficient in most cases.
14
15However, please note that there are some scenarios that will require
16administrator's attention and some testing of exact requirements before
17deploying Knot DNS to a production environment. These cases include
18deployment for a large number of zones (DNS hosting), large number
19of records in one or more zones (TLD), or large number of requests.
20
21CPU requirements
22----------------
23
24The server scales with processing power and also with the number of
25available cores/CPUs. Enabling Hyper-threading is convenient if supported.
26
27There is no lower bound on the CPU requirements, but it should support
28memory barriers and atomic instructions (i586 and newer).
29
30Network card
31------------
32
33The best results have been achieved with multi-queue network cards. The
34number of multi-queues should equal the total number of CPU cores (with
35Hyper-threading enabled).
36
37Memory requirements
38-------------------
39
40The server implementation focuses on performance and thus can be quite
41memory demanding. The rough estimate for memory requirements is
423 times the size of the zone in the plain-text format. Again this is only
43an estimate and you are advised to do your own measurements before
44deploying Knot DNS to production.
45
46.. NOTE::
47   To ensure uninterrupted serving of the zone, Knot DNS
48   employs the Read-Copy-Update mechanism instead of locking and thus
49   requires twice the amount of memory for the duration of incoming
50   transfers.
51
52Operating system
53================
54
55Knot DNS itself is written in a portable way and can be compiled
56and run on most UNIX-like systems, such as Linux, \*BSD, and macOS.
57
58Required libraries
59==================
60
61Knot DNS requires a few libraries to be available:
62
63* libedit
64* gnutls >= 3.3
65* liburcu >= 0.5.4
66* lmdb >= 0.9.15
67
68.. NOTE::
69   The LMDB library is included with Knot DNS source code. However, linking
70   with the system library is preferred.
71
72Optional libraries
73==================
74
75International Domain Names support (IDNA2008 or IDNA2003) in :doc:`kdig<man_kdig>`:
76
77* libidn2 (or libidn)
78
79Systemd's startup notification mechanism and journald logging:
80
81* libsystemd
82
83Dnstap support in :doc:`kdig<man_kdig>` or module :ref:`dnstap<mod-dnstap>`:
84
85* fstrm (and protobuf-c if building from source code)
86
87Linux :manpage:`capabilities(7)` support, which allows the server to be started
88as a non-root user/group, binding to privileged ports (53), and giving up all
89its capabilities, resulting in a completely unprivileged process:
90
91* libcap-ng >= 0.6.4
92
93MaxMind database for **geodb** support in module :ref:`geoip<mod-geoip>`:
94
95* libmaxminddb0
96
97DNS-over-HTTPS (DoH) support in :doc:`kdig<man_kdig>`:
98
99* libnghttp2
100
101The :ref:`XDP functionality <Mode XDP>` and :doc:`kxdpgun <man_kxdpgun>`
102tool. These are only supported on Linux operating systems. See the chapter
103:ref:`Mode XDP <Mode XDP_pre-requisites>` for software and hardware
104recommendations.
105
106* libbpf >= 0.0.6
107* libmnl (for kxdpgun)
108