[AusNOG] DNS forwarders (was Re: IPv6: Who's dual stacked? Why don't I look stacked?)

[Paul Gear]

On 03/08/2013 11:22 AM, Greg McLennan wrote:
> ...
> Only thing to be mindfull is to make sure the DNS set in the mikrotik 
> points at a suitable public or ISP's DNS server that can also pass 
> AAAA records.

I've never understood why anyone bothers with upstream DNS forwarders [1].

Are there some strong technical (e.g. customer experiences breakage) or 
community-minded (e.g. the top-level servers can't handle it) reasons 
why we shouldn't just let all DNS queries go to the root? Most people 
seem to set their TTLs pretty low anyway [2], so it seems like a 
pointless exercise.

Paul

[1] Except for non-performance-related reasons, e.g. OpenDNS.

[2] I'm too lazy to look up the reference, but i read a study of DNS 
TTLs which found that approximately (making up the numbers here) 95% of 
all TTLs were < 1 day.  Of those < 1 day, 95% were < 1 hour.  Of those < 
1 hour, 95% were < 5 minutes.