All of this applies to DNS providers as well: registrars, web hosts, ISPs, managed DNS operators, and so on. What changes is the scale one is operating at and the mechanics of effecting step 3, that of adjusting your DNS setup in response to outages or degraded conditions.
Here, we refer back to our Chapter 12, Nameserver Considerations, when it comes to selecting address space for numbering your nameservers. Ideally, you control its address space so that you can easily move traffic around, using routing announcements if you have to.
This is what I was alluding to Chapter 12, Nameserver Considerations, about moving traffic into DDoS scrubbing centers during an attack using BGP.
One model we used for awhile with great success was a combined anycast/unicast architecture, where under normal course operations, a particular nameserver entity was an anycast-deployed...
