> The reason why I got interested was because section 8.2 of > draft-ietf-dnsop-ipv6-dns-issues-08.txt (see below) shows that the > application should be able to be aware of the TTL of the records, > easily, so that it could discard expired records from the memory if > it's built around in such a way that it would be feasible to do so.
Please recall that the purpose of the TTL is for cache coherency, not a statement on the quality nor timeliness of the data in DNS. Similarly, the validity periods expressed in the signature records are not statements on the validity of the data, but the validity of the ancillary security data.
"Expired records" is a concept alien to DNS. (A zone may be expired to a slave server.)
> As it is, the applications typically query a name when they start and > use it forever, irregardless of the TTL. (And if the > application-resolver interface needs work in any case....)
DNS is designed to be timeless service. It's up to applications to be as dynamic as they want to be. If applications assume incorrectly about the DNS, havoc will ensue. Applications should not assume anything about the timers and clocks inside DNS.
OT: In my pre-DNS days, I once made my own simple lookup system. The app looked up a name, got the address, and tried to complete the handshake of the transport layer. If that failed, the app would then report back to the lookup system that the address was bad. When the app wanted to connect again, it would lookup the name until a new address was registered. If no address was received, it would set a timer and try again later. This was mostly event driven, not timer-based - accomplishing what seems to be desired above without needing to pass timer information across the lookup service interface.
My point is - applications developers ought to rely on DNS at it's service's face value, not by inferring anything in the ancillary data. If application developers try to read between the lines, we muddle the architecture of the Internet and will end up with a "house of cards."
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Edward Lewis +1-703-227-9854
ARIN Research Engineer
"I can't go to Miami. I'm expecting calls from telemarketers." - Grandpa Simpson. . dnsop resources:_____________________________________________________ web user interface: http://darkwing.uoregon.edu/~llynch/dnsop.html mhonarc archive: http://darkwing.uoregon.edu/~llynch/dnsop/index.html
