At 07:22 AM 5/29/00 , Markku Savela wrote:
>
>> There is no specification on the relationship of the queries is it
>> first match, match all that apply, or some other one.
>>
>> Then there is the issue of error reporting, if there is a query for
>> first A6 and secondly A, and A6 does not exist is but A does is this
>> an error or not ?
>
>If there are no deployed software that implements the multiple query
>feature, would there be a window for actually specifying some working
>semantics for it now?
Yes and NO.
DNS implementations are just starting to catch up with the
many new features that have been added in the last few years, Dynamic
Update, Incremental Zone transfer, IPv6 support (AAAA, A6, DNAME and
bit string labels) and DNSSec. There is going to be a lag in deployment
any new features.
>......The goals being
>
> - detection the old servers that don't support multiple query
> ("format error" seems to be a tell tale from some?)
>
There is discussion going on how to find out in general what features a
particular server supports.
> - minimise the transactions for AAAA,A,A6 (it would be such a neat
> package, with one hostname appearing only once using the DNS
> compression...)
>
> - define rules how to reply in case not all queries succeed (the
> particular goal being the needs of IPv4/IPv6 transition). Can think
> few starters
>
> - if all are in cache, return all
> - if some are in cache, return them separately, but
> proceed with query
> - if some name results error, and some not, perhaps return a
> separate error reply for them?
>
> - wouldn't multiple queries be more clean for some other purposes
> too? Query A or MX? (instead of messy "addional section..." :-)
>
Multiple queries have certain attractiveness to them but once you think the
issue through, things get quite complicated.
If your client does not care what version of IP is used, then ask in parallel,
if it has preference express it in query ordering.
Saving bits on the wire with compression in query is not a factor, getting
back a truncated answer in response to a multiple question request
is a bigger issue.
Olafur
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