howto know if a query was delegated to cache

harish badrinath harishbadrinath at
Tue Jul 26 04:50:56 UTC 2011

> Whatever you're trying to accomplish, it's would not appear to be consistent
> with the founding RFCs for DNS:
I am not trying to modify when/how/which "upstream name server" is
contacted, i am not invalidating cached data at my will. I am not
trying to modify requests/responses.

Basically i am trying to implement dns based acls instead of I.P based ones.
sites using CDN's and sites like google yahoo can resolve to different IP's.

For this, i maintain a list of domains that need to be white listed
and their IP's.
If bind is resolving for the entire LAN for example, then the subnet
can access a domian/subdomain.

Next comes list node stale content deletion, the easiest way that i
can think of doing this is:
when ever bind is responding from internal cache, do nothing
when ever bind has to contact resolvers to get the job done, get final
response, parse it, update list, update shared memory (other processes
actually implement the ACL code).

Basically i want to know if a client/query structure has a state
representation/function that can tell
(a) If the current client structure was filled up with data from
bind's internal cache db.
(b) And/Or, If the current query structure was filled up with data
from bind's internal cache db.

It has very little to do with contacting when/how/which external
caching/resolving dns servers.


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