[dns-operations] opting in to stupid DNS tricks

[Matthew Pounsett]

On 21-Feb-2011, at 06:23, Jim Reid wrote:

> BTW, I still don't understand why CDNs are abusing the DNS to solve  
> something that is actually a routing problem. What's wrong with  
> anycasting the IP address(es) of the web site or whatever? That way,  
> the network figures out the truly optimal path (peering policies  
> aside) between the end client and the content provider's server.  
> Yes, I realise this may break TCP connections sometimes, but how  
> much of a real problem is this? Has anyone got hard data about this?

As an anycast DNS provider, my answer to this is: because BGP  
optimizes for the shortest AS path, not the shortest path, or the  
lowest RTT, or the most bandwidth, or the most capacity.  At $DAYJOB  
we give the same answer from everywhere, but we don't just rely on BGP  
to give great performance.  Anycast gives availability, and helps to  
sink regional DDoS.. it does not provide performance.