random question about the internals of bind

[Kevin Darcy]

Barry Margolin wrote:

> In article <86nlar$hv$1 at net.indra.com>, Kirk Johnson <tuna at indra.com> wrote:
> >i'm curious if anybody can tell me what happens to this state (the
> >"approximate" round-trip times associated with each NS record) when
> >the TTL on the NS records expires. when the same group of NS records
> >are refetched, is any of the state that was associated with the
> >previous instance of those NS records (before the TTL expired)
> >preserved? (this is the simple case -- assume that bind gets back
> >exactly the same NS records as it had previously.)
>
> I believe the state is associated with the server's IP address, not the NS
> record.  So the expiration of the NS record doesn't have any impact on it
> -- there could be other NS records for other domains that point to the same
> server.

Actually, it appears the RTT information is stored in the A record for the
nameserver. So, when the A record expires, the RTT information for that nameserver
is lost. (Complicating matters even further, the "hints" A records are separate
from the regular A records, which explains why one can see the same nameserver A
record listed twice in a database dump, with identical values except the RTT).


- Kevin