Disadvantages of BGPDNS
Each server requires as many IP addresses as it is connected to ISP’s
- Which is relative, AS-based multi-homing needs at least a /24, here in this example with three ISP‘s I can get away with 3x /27 or so
For cached DNS resource records; only timeout- based convergence
Additional load on the DNS system
- Which doesn‘t seem to be a problem (Thanks Akamai!)