Re: Comcast residential DNS contact

[Pavel Odintsov <pavel.odintsov () gmail com>]

Hello!

But any other DNS type can be used for DNS amplification. RRL is right
solution for amplification issue. I recommend NSD DNS server because
it's reliable, has complete support of DNSSEC, IPv6 and RRL.

On Wed, Dec 3, 2014 at 5:08 PM, Stephen Satchell <list () satchell net> wrote:
> On 12/03/2014 04:04 AM, Niels Bakker wrote:
> > * shortdudey123 () gmail com (Grant Ridder) [Wed 03 Dec 2014, 12:54 CET]:
> > > Both of Google’s public DNS servers return complete results every time
> > > and one of the two comcast ones works fine.
> > >
> > > If this is working by design, can you provide the RFC with that info?
> >
> > An ANY query will typically return only what's already in the cache.  So
> > if you ask for MX records first and then query the same caching resolver
> > for ANY it won't return, say, any TXT records that may be present at the
> > authoritative nameserver.
> >
> > This could be implementation dependent, but Comcast's isn't wrong, and
> > you should not rely on ANY queries returning full data.  This has been
> > hashed out to tears in the past, for example when qm**l used to do these
> > queries in an attempt to optimise DNS query volumes and RTT.
>
> At the ISP I consult to, I filter all ANY queries, because they have
> been used for DNS amplification attacks.



-- 
Sincerely yours, Pavel Odintsov