DNS Master Migration

[Ian Killer]

I will be migrating my DNS master from one server to another, and I'm trying to build a strategy to do so. Is an outage required, would you recommend temporarily running two masters?

Our current master server is running UX 10.20. Can you foresee any problems arising from making the new DNS master a v11 system? (Apart from the "_" problem)

[Tommy Brown]

We recently migrated from 10.20 to 11.0 with very little problems. You can bring up a new Master get it debugged then bring up the Slave (if configured), then change all the clients (etc/resolv.conf). We had a little trouble, thanks to bad typing skills, but I mainly moved the files from one system to the other.
Tommy

[Tim Malnati · Accepted solution]

I would probably bring up to new machine and get things fully operational as a master. Test everything to make sure resolutions are right, then repoint any existing slaves over to it. Then I would make the original master into a slave for the new machine. Now it's time to make any DHCP modifications necessary so that client machines become aware of the new machine. Any clients with static DNS configuration need to be taken care of as well. I would probably leave the old machine running for a week or two just to make sure that as many clients as possible find their way to the new machine. This way you should have plenty of time for all the clients to know where to go (all DHCP leases should have expired) and for all the DNS ttl's to expire.

[John Bolene]

When I did this, I built the new master (which was on a different network segment) and then gradually pointed all the clients to the new machine by changing their /etc/resolv.conf file. After they were all moved, I turned on DNS debug on the old master and lo and behold, a few clients were still using it. I suspect that its entry was cached somewhere but never found it. I took down named on the old master and a few of the clients got one DNS error but then switched to use the new server. It seemed that they used the old server until they could no longer get to it. I never figured out why this happened.
Reconfiguring the X-terminals that pointed to the old DNS server was more frustrating. I changed all 2000+ config files and told the X-terminals to reread their config file. Most of them switched at that point, but around 10% were stubborn and had to be rebooted. A handful had to have their NVRAM information destroyed and rebuilt manually before they would read their config file and use the new server.