[bind10-dev] sorting RDATA in-memory

[Robert Edmonds]

JINMEI Tatuya / 神明達哉 wrote:
> BIND 9 sorts RRs of the same RRset in the DNSSEC order when it loads
> the records into memory (unless the special compile time options is
> specified).  Is there any reason for this behavior?  Obviously we need
> to sort them when we need to compute the signature of the RRset, but I
> don't see the need for it in answering queries.  I'm curious about
> whether there's any other reason for the convenience of calculating
> the signature.

sorting the RRset is probably the easiest way to do duplicate
suppression:

    "It is meaningless for two records to ever have label, class, type
    and data all equal - servers should suppress such duplicates if
    encountered."

(RFC 2181)

-- 
Robert Edmonds
edmonds at isc.org