--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dns.rst	Mon Jan 11 13:31:07 2016 +0200
@@ -0,0 +1,99 @@
+.. -*- coding: utf-8; -*-
+.. include:: HEADER.rst
+
+======
+ DNS.
+======
+
+About DNS resolving protocol.
+=============================
+
+Default port for name resolving is ``53``::
+
+  $ nslookup -port=53 microsoft.com
+
+Debugging name resolution.
+==========================
+::
+
+  $ nslookup -debug microsoft.com
+
+Dumping all available resords::
+
+  $ nslookup -type=any microsoft.com
+
+IP from host name.
+==================
+
+This request is for the ``A`` record and default for ``nslookup`` command::
+
+  $ nslookup defun.work
+  $ nslookup -type=a defun.work
+
+Host name from IP.
+==================
+
+If that information available::
+
+  $ nslookup -type=ptr 8.8.8.8
+
+
+List authoritative NS for domain.
+=================================
+::
+
+  $ dig ns defun.work
+  $ nslookup -type=ns defun.work
+
+List MX records for domain.
+===========================
+::
+
+  $ dig mx mail.google.com
+  $ nslookup -type=mx mail.google.com
+
+List SOA records for domain.
+============================
+
+SOA ("Start Of Authority") Record for a domain provides technical information
+about the domain::
+
+  $ dig soa defun.work
+
+Human readable format can be viewed via::
+
+  $ nslookup -type=mx defun.work
+
+    origin = ns1.mindsandmachines.com
+    mail addr = admin.mindsandmachines.com
+    serial = 2011091101
+    refresh = 10800
+    retry = 7200
+    expire = 604800
+    minimum = 86400
+
+Email adress for domain administrator is ``admin@mindsandmachines.com`` for
+above output.
+
+List domain names.
+==================
+::
+
+  $ dig ns dp.gov.ua
+  ...
+  ;; ANSWER SECTION:
+  dp.gov.ua.              3600    IN      NS      ns.giknpc.com.ua.
+  ...
+
+  $ dig @ns.giknpc.com.ua dp.gov.ua AXFR
+  ...
+  dp.gov.ua.              3600    IN      MX      200 relay2.giknpc.com.ua.
+  dp.gov.ua.              3600    IN      A       195.64.190.1
+  adm.dp.gov.ua.          3600    IN      A       195.64.190.1
+
+How reread config file?
+=======================
+
+FreeBSD::
+
+  $ named.reload