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I'm trying to configure two virtual servers running Ubuntu to act as primary and secondary DNS and DHCP servers in my lan.

I was able to get bind9 working as master and slave DNS servers.
I was able to get dhcpd server working as master and slave.
I was even able to follow a tutorial and configure the master dhcp server to automatically update the master dns server.

But when I put everything together the automatic dns update breaks. I don't understand how to configure the slave dhcp server to update the dns server (which one should it update?), and the master dhcp server fails to update the master dns (I see time-out error in the syslog)

Can someone point me to a tutorial that addresses both redundancy and automatic updates? Or maybe explain what I'm doing wrong in my configuration. I cannot see/ to get both features to work together.

Thank you

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Sure, but firstly provide configuration... Btw. I hope, by master/slave DHCP configuration you mean configuration with failover link. We have such configuration in our company on hundreds of dhcp servers and it works without bigger problems. –  plluksie Dec 18 '10 at 13:49

2 Answers 2

Upon request, I'm pointing you to this detailed tutorial: HOWTO Design a fault-tolerant DHCP + DNS solution

It's based on Red Hat / CentOS, but the configurations should work on Ubuntu too, with little adaptations.

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The problematic point is DNS updates. The only place where DNS can be updated is a master DNS server. Master can be only one, and once it fails, slave will answer DNS queries, but DNS can not be updated anymore.

I could not find any DNS server software which would support multi-master setup. My conclusion is that using available software the only option is master-slave, and if master fails, it's probably possible (but not easy at all) to setup a failover where slave will "become" master.

Multi-master would be possible if DHCP server could send updates to two DNS servers...

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