Can SERVFAIL be incorrectly returned through caching?

[Pete Ehlke]

On Mon, Jul 01, 2002 at 05:10:10PM +0100, Simon Waters wrote:
> 
> A BIND 9.2.1 server on Redhat Linux 7.0 built from source,
> default options.
> 
> After a brief period of being disconnected, and following a
> reconnect a dig to the local nameserver for a record returned
> SERVFAIL.
> 
> This continued after the name server was reconnected for a
> noticable period.
> 
> The SERVFAIL error was reported long enough for me to manually
> follow the resolution procedure down from the root name servers,
> and confirm that nothing obvious was wrong (routing/DNS
> delegation).
> 
> So course of events....
> 
> disconnect from internet.
> Look up record - SERVFAIL
> Reconnect to internet
> Look up record - SERVFAIL
> Lookup up other stuff appear okay.
> Lookup uk NS - okay
> Query co.uk NS for ISP NS - okay
> Lookup ISP NS - okay
> Query ISP NS for record - okay
> Lookup record - SERVFAIL
> Lookup record - okay
> 
I suspect that it was more completely described like this:

disconnect from internet
interface_interval expires, named scans interfaces, deletes absent connection
reconnect
look up record not in local cache- SERVFAIL
look up stuff in cache- okay
etc...
interfaces get scanned again, normal functionality reappears

Sound reasonable?

-P.