DNS

Domain name service

Check mail record with dig

   1 dig mx bitarus.allowed.org

Check mail record with dig directly in name server

   1 dig mx bitarus.allowed.org @ns.bitarus.allowed.org

Check reverse dns

   1 dig -x 54.68.9.58

Ask for Reverse DNS for EC2 Elastic IP address

https://portal.aws.amazon.com/gp/aws/html-forms-controller/contactus/ec2-email-limit-rdns-request

Dynamic DNS Raspberry pi

In bind9 server

   1 # change apparmor in ubuntu 
   2 apt install apparmor-utils
   3 sudo aa-complain /usr/sbin/named
   4 service bind9 restart
   5 
   6 cd /tmp # bind server
   7 dnssec-keygen -a HMAC-SHA512 -b 512 -n USER rpi.dyn.bitarus.allowed.org.
   8 # secret contains the Key: value
   9

/etc/bind/keys.conf

   1 key rpi.dyn.bitarus.allowed.org. {
   2     algorithm HMAC-SHA512;
   3     secret "???????";
   4 };

/etc/bind/named.conf

   1 include "/etc/bind/keys.conf";
   2 zone "bitarus.mooo.com" IN {
   3   type master;
   4   file "/etc/bind/bitarus.mooo.com.hosts";
   5   allow-update { key "rpi.dyn.bitarus.allowed.org."; };
   6 };

/etc/bind/bitarus.mooo.com.hosts

Subdomain bitarus.mooo.com

   1 $ORIGIN .
   2 $TTL 604800     ; 1 week
   3 bitarus.mooo.com        IN SOA  bitarus.mooo.com. root.bitarus.mooo.com. (
   4                                 6          ; serial
   5                                 604800     ; refresh (1 week)
   6                                 86400      ; retry (1 day)
   7                                 2419200    ; expire (4 weeks)
   8                                 604800     ; minimum (1 week)
   9                                 )
  10                         NS      bitarus.mooo.com.
  11                         A       54.68.9.58
  12                         MX      5 mail.bitarus.mooo.com.
  13                         TXT     "keyx=valuex"
  14 $ORIGIN bitarus.mooo.com.
  15 labs                    A       54.68.9.58

   1 sudo chgrp bind /etc/bind
   2 sudo chmod g+w /etc/bind
   3 sudo chown -R bind:bind /etc/bind
   4 service bind9 restart

In raspberry pi

   1 cd /tmp
   2 scp  user@bitarus.allowed.org:/tmp/K*dyn* . 
   3 mkdir ~/rpiDdns
   4 mv Kr* ~/rpiDdns/
   5 cd  ~/rpiDdns/
   6 chmod 0400 Krp*
   7 sudo apt update
   8 
   9 #vim nsupdate-rpi.sh
  10 logger "Running nsupdate-rpi.sh"
  11 EXT_IP=$(wget -qO- http://ifconfig.co/ip)
  12 KEY="/home/pi/rpiDdns/Krpi.dyn.bitarus.allowed.org.+165+55648.private"
  13 echo "Key: $KEY"
  14 
  15 cat <<EOF | nsupdate -k "$KEY"
  16 server bitarus.allowed.org
  17 zone bitarus.mooo.com
  18 update delete rpi.bitarus.mooo.com. A
  19 update add rpi.bitarus.mooo.com. 600 A $EXT_IP
  20 show
  21 send
  22 EOF
  23 
  24 chmod 755 nsupdate-rpi.sh
  25 crontab -e
  26 */10 * * * * /home/pi/scripts/nsupdate-rpi.sh

chucknorris host

   1 named-checkconf /etc/bind/named.conf
   2 named-checkzone bitarus.mooo.com /etc/bind/bitarus.mooo.com.hosts
   3 service named restart 
   4 ping chucknorris.bitarus.mooo.com

nslookup

   1 nslookup
   2 > server x.example.org
   3 Default server: x.example.org
   4 Address: 1.2.3.4#53
   5 > set type=any
   6 > x.example.com 
   7 Server:         x.example.org
   8 Address:        1.2.3.4#53
   9 
  10 Name:   x.example.com
  11 Address: 1.2.3.4
  12 > exit

-  ⇤ ← Revision 9 as of 2025-01-13 18:48:34 → 
  Size: 2514
  Editor: vitor
  Comment:
+   ← Revision 15 as of 2026-09-18 21:46:32 → ⇥
  Size: 3028
  Editor: vitor
  Comment:
-Deletions are marked like this.
+Additions are marked like this.
 Line 1:
-= dns =
+<<TableOfContents(2)>>

= DNS =
-Line 24:
+Line 26:
+=== In bind9 server ===
-Line 32:
+Line 36:
+# secret contains the Key: value
}}}
-Line 33:
+Line 39:
-# secret contains the Key: value
# vim /etc/bind/keys.conf
+=== /etc/bind/keys.conf ===
{{{#!highlight sh
-Line 39:
+Line 45:
+}}}
-Line 40:
+Line 47:
-# vim /etc/bind/named.conf
+=== /etc/bind/named.conf ===
{{{#!highlight sh
-Line 47:
+Line 55:
+}}}
-Line 48:
+Line 57:
-#vim /etc/bind/bitarus.mooo.com.hosts
+=== /etc/bind/bitarus.mooo.com.hosts ===
Subdomain bitarus.mooo.com
{{{#!highlight sh
-Line 61:
+Line 72:
+                        TXT	"keyx=valuex"
-Line 63:
+Line 75:
+}}}
-Line 64:
+Line 77:
+{{{#!highlight sh
-Line 68:
+Line 82:
+}}}
-Line 69:
+Line 84:
-# In raspberry pi
+=== In raspberry pi ===
{{{#!highlight sh
-Line 105:
+Line 121:
+== nslookup ==
{{{#!highlight sh
nslookup
> server x.example.org
Default server: x.example.org
Address: 1.2.3.4#53
> set type=any
> x.example.com 
Server:		x.example.org
Address:	1.2.3.4#53

Name:	x.example.com
Address: 1.2.3.4
> exit
}}}