Some useful measurements from Geoff, I'm not sure what the thesis is or it wasn't stated clearly enough for me at the outset, and the conclusion appears to be to use anycast for authoritative nameservers because it's recursives' faults.
Anyway: Recursives don't consistently do a good job of picking the fastest-responding authoritative. Apparently the description of how to do this in RFCs is unclear (not to me). Unbound uses a measure (400ms) which is conflated with a "diameter of the public internet". My interpretation is that BIND does the best job of honoring the RFC's intent in this regard.
I concur that faster is generally better, but on the other hand recursives shouldn't be running with a cold cache except on startup. Parallelization of requests isn't addressed and neither is for instance the impact of long CNAME chains or requiring resources from numerous instances of disparate authoritative infrastructure (or CNAME chains requiring resources from disparate infrastructure).
So this kind of seems to me like telling authoritative operators what they want to hear and probably already know / suspect.
Anyway: Recursives don't consistently do a good job of picking the fastest-responding authoritative. Apparently the description of how to do this in RFCs is unclear (not to me). Unbound uses a measure (400ms) which is conflated with a "diameter of the public internet". My interpretation is that BIND does the best job of honoring the RFC's intent in this regard.
I concur that faster is generally better, but on the other hand recursives shouldn't be running with a cold cache except on startup. Parallelization of requests isn't addressed and neither is for instance the impact of long CNAME chains or requiring resources from numerous instances of disparate authoritative infrastructure (or CNAME chains requiring resources from disparate infrastructure).
So this kind of seems to me like telling authoritative operators what they want to hear and probably already know / suspect.