So have A record queries. Do you filter those as well? Jared Mauch
On Dec 3, 2014, at 9:08 AM, 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.