I am looking for a commercial DNS service that provides geo-directionality. Suppose I have 4 data centers scattered thruout the world and want users to hit the closest data center based on proximity checks (pings, TTLs, latency, load, etc.). I know one can "roll their own", using various geo-locational data from companies like Maxmind. I am *not* interested in that. I am *not* interested in applicances like the Cisco ACE GSS 4400 either (that do this as well): http://www.cisco.com/en/US/products/hw/contnetw/ps4162/
What I am looking for is a commercial DNS service.
Another service I know about is the Ultradns (now Neustar) Directional DNS: http://www.neustarultraservices.biz/solutions/directionaldns.html
But this service is based on statically defined IP responses at each of their 14 sites so there is no proximity checking done.
Proximity checking is very important and I have run into cases as you have where it is needed. Even taking your example of a location in Toronto, peering arrangements would cause not all Toronto ISPs to act the same and therefore RTT could vary not just by 15ms but sometimes by 150ms. Now imagine I have a data center in Tokyo. Do I send all users from Hong Kong, Singapore, Korea, Taiwan and Australia to that data center in Tokyo or perhaps some would do better going to my data center in LA?
In regards to the Neustar staticly defined IPs - I was only able to uncover that after digging.
Thanks for the Netriplex lead. I like Neustar for their bullet proof DNS but not so much for their directional DNS service.
Yes, and that's how anycast works: it directs traffic to the
_topologically nearest_ server. So as long as there's a DNS server
topologically near your data server, your users will get the topologically
nearest of your servers. Which is why so many content folks _do_ roll
their own: to ensure fate-sharing between the DNS traffic which
effectively selects the data server, and the eventual data traffic.
If you're doing things on the Internet, instead of the physical world,
topological distance is presumably of much greater interest than whatever
geographic proximity may coincidentally obtain.
Except Hank is asking for true topological distance (latency / throughput / packetloss).
Anycast gives you BGP distance, not topological distance.
Say I'm in Ashburn and peer directly with someone in Korea where he has a node (1 AS hop), but I get to his node in Ashburn through my transit provider (2 AS hops), guess which node anycast will pick?
