Hi, I'm not sure whether I'm imagining things or whether this is a real problem .. comments please! :-)
There seems to be an obvious problem with caching and additional data, if the additional data is partial, and the additional data is filtered using some criteria to avoid going over the 512 byte limit. For example, assume that www.example.com has A record to 1.2.3.4 and AAAA record to 2001:db8::1, and some other records which imply that the response (with full additional data) does not fit in the response. Assume that the implementation at the servers is made so that instead of giving back Truncated response, it filters the response somehow: in this example by omitting AAAA records. Now, assume a host queries www.example.com through a couple of caching servers. Due to the response size limits, the caching servers cache only the A records (etc.). Now, everybody whose queries for www.example.com go through these caching servers gets back only A records, or? So, in some sense I think "it's better to have no data at all than impartial cached data". Am I imagining things or is "additional section selection/filtering" a really bad idea especially if at least one entry of each available record type is not represented? And the filtering methods proposed earlier and in particular in draft-hall-qtype-addr-01.txt section 4 are pretty broken? If so, maybe there should be some kind of data on how many records of each type exist (or at least, "at least one record of type Foo exists"), even though there was no space for all the records to be sent? -- Pekka Savola "You each name yourselves king, yet the Netcore Oy kingdom bleeds." Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings . dnsop resources:_____________________________________________________ web user interface: http://darkwing.uoregon.edu/~llynch/dnsop.html mhonarc archive: http://darkwing.uoregon.edu/~llynch/dnsop/index.html
