DNS Updates

Keys

We configured the DNS Servers to allow updates using keys. Those keys need to be available on the system that sends the DNS updates. The keys are already on the DHCP server, so it makes sense to make the DNS updates from the DHCP server.

nsupdate

The utility to make DNS updates is called nsupdate. When running it, it takes two important parameters -v to send updates by TCP rather than UDP and -k to tell it which file the update key is in.

Install

apt-get install dnsutils

Update

nsupdate -k /etc/dhcp/ddns-update.kallenberg.dk -v

You now have a prompt where you can enter the update commands.

Adding a Host

dhcp01

IP-address: 192.168.1.36

update add dhcp01.kallenberg.dk 86400 A 192.168.1.36
send
update add 36.1.168.192.in-addr.arpa. 86400 PTR dhcp01.kallenberg.dk.
send

Removing a host

dhcp01

IP-address: 192.168.1.36

update delete dhcp01.kallenberg.dk IN A 192.168.1.36
send
update delete 36.1.168.192.in-addr.arpa. PTR dhcp01.kallenberg.dk.
send

References

• http://www.rtfm-sarl.ch/articles/using-nsupdate.html