redirect dns query where router is offline

["wolk" <wolk@jablko.one.pl>]

I try to do redirection of dns query. 
For example: 
The link to internet is offline. Client wants to view some www page. I want 
to  redirect client to my www server on local network(page has the the 
information that internet is not avilable). 
On my router(openbsd 3.5) works squid in transparent mode. 
How to do this?     
jacek
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