Re: [Asrg] RFC 6471 and "listing the Internet" as a punishment

[Steve Atkins <[e-mail]>]

On Jan 25, 2012, at 3:26 PM, Paul Smith wrote:

> On 25/01/2012 22:57, SM wrote:
>> 
>> 
>> Are there any examples of DNS "caching services" set up to reduce network traffic and why it is being done?
> 
> Hang on - isn't that the whole point of DNS caching? If people didn't care about network traffic, no one would cache anything, they'd just resolve the addresses every time. Apart from increased network traffic, resolving every time would be much better, as there'd be no stale data.
> 
> So, pretty much every caching DNS server is there to reduce network traffic. Isn't it?

Partly, yes. It also reduces latency significantly (helped by very high cache hit rates near the root of the tree).

(Queries to DNSBLs and similar trees - e.g. in-addr.arpa - do damage that somewhat, by creating a large number of different queries few of which are reused, hence tending to evict higher value records from the cache. But that's orthogonal to what we're discussing here, really.)

Cheers,
  Steve