last few weeks I have seen many discussions over UDP truncating and using
minimal-responses yes; to prevent BIDN from doing that.
I've read article stating that nameserver should avoid truncating packets
even by skipping additional and authority sections in its responses, which
should mean that using minimal-responses would not help.
However, I've seen a few mails mentioning that a query can get truncated
when the authority section is too big and advices to turn
minimal-responses
on.
Reading the 9.9.2 docs and even looking at the sources (I am not a C
coder)
did not help me with this.
On 27.11.12 17:41, Mike Hoskins (michoski) wrote:
It seems it should help... less bits in the packet relating to additional
and authority should leave room for other data.
OTOH, some of the data may be needed (later), and adding them into response
may avoid need for another request.
That said, I think the better way (when possible) is to adjust RRs not to
return too much data (e.g. NS, A, etc. not returning more than ~8 hosts
-- which in turn could be multicast, load balanced, etc to get the desired
scale).
Akamai, for example, defaults to limiting up to 8 RDATAs per RR (or
however you'd describe that). If you add 20 As for a name you'll rotate
through 8 at a time. You can request more at your own risk...they assume
you'll ensure the larger answer will fit in a UDP packet and not cause TCP
responses which cripple performance.
I know. But there are cases you just have much of data in the DNS and what I
am asking is, if BIND really does skip authority section, if it helps to
avoid sending truncated packets.
If it does, the minimal-responses does NOT affect packet truncation. if it
does not, I ask why...
--
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