whether SERVFAIL is cached by caching server

[Barry Margolin]

In article <dnbg4e$2cqn$1 at sf1.isc.org>,
 Sanjib Das <Sanjib.Das at lntinfotech.com> wrote:

> Hi
> I have setup a local domain my.domain. & it consists of two machines...
> I configured one of them as primary server for my domain & another one
> as caching server .For both these servers I'm using BIND-9.2.4 package
> whenever I send query (using 'dig' command).....
> from the second machine (machine where the caching server is running 
> locally) first it looks into its own cache....if its available it sends 
> from there 
> itself... otherwise sends it to the primary server...
> Now say I got a SERVFAIL in the reply.... in this case whether my
> caching server will cache this information...coz I found that
> whenever I send the same query to the same server(second time after 
> getting SERVFAIL)..it sends to the server again....that means what I 
> believe the resolver (caching server) is not cqaching this kind 
> of(SERVFAIL)
> response....
> 
> Please let me know whether my analysis is right or wrong....

Your analysis is correct.  Errors are not generally cached, only valid 
responses are.  As a result, it's not uncommon to see high volumes of 
repeated queries due to misconfigured servers like this.

-- 
Barry Margolin, barmar at alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***