Keep it simple....
Rather than having a huge cluster with a gazillion domains on it, just have a number of smaller servers, when you register a domain the control panel automatically assigns you to the latest dns servers.
That way you don't need to run complicated software and the zones don't take an age to load etc etc. When you do have an issue its isolated to a subset of all the domains registered with you rather than every domain. You can limit how many domains are on any one set of servers and upgrade them if the performance starts to take a hit. If you plan your capacity this should never happen.
The down side, a few more servers to run. Up side common kit, common components easy hardware fixes.
On the subject of using other dns servers as a backup, this would be a good option but reg-123 like many reg-123 won't allow you to do this automatically as they have disabled zone transfers and there is no option to enable it.
I guess you could manually update both but that would lead to a situation where at best your dns looks (even if it isn't) out of synch.
I migrated all my domains from reg-123 a while ago once pipex took over and it started going down hill, there was just one too many cockups so I bit the bullet and moved elsewhere (domainmonster.com as it happens).
As for "Whine Whine, Whinge Whinge" By Graham Wood you say you haven't been affected, of course not as you state you run your own dns servers so it would not affect you.
Unfortunately not everyone is as lucky or perhaps didn't realise the importance of dns servers. Perhaps this is a wake up call for many. Its pointless spending thousands on your web site and advertising and then losing your business for the sake of a few pounds spent on some decent dns servers run by a company who provides reasonable support, monitors its kit correctly and can fix things in a reasonable time frame.
A few pointers for anyone looking for a new dns provider.
Ensure they have at least 2 dns servers, preferably 3. At least one should be in a different location/data center. Ensure the dns servers are in the country you expect, many so called uk providers are actually hosted in the US which means slower lookups and more chance of problems due to network issues.
If you are also using them as a registrar also check if it costs to transfer away in the event they don't work out and make sure this can be done automatically via a control panel without their intervention. If its costs money or you can't do it online yourself then avoid them.
Finally check your dns by using someone like dnsreport.com whenever you change it to make sure its working correctly. We regularly get customers querying alerts we send them and when we check their dns setup we generally find it is not totally valid. The most common mistake is different name servers specified at the root servers to those in their own name server records.
Biting the hand that feeds IT
