Queries using forwarders

John Miller johnmill at brandeis.edu
Mon Jun 3 21:31:13 UTC 2013

Hi Mike,

To keep my answer simple, if BIND is set up to allow recursion, and gets 
a recursive query for a zone it's not authoritative for, it'll:

1) Answer from cache
2) pass the query off to the configured forwarders
3) If the forwarders are unavailable, follow delegation itself to answer 
the query.

BIND is only authoritative for a zone if there's a

zone {}

block for it (or its parent zone).

As Steven mentioned, you can set BIND up to act as authoritative for a 
domain you don't own (e.g. malware.site.tld) so that your users get a 
false answer to their queries.  It's a pretty common 
anti-malware/anti-spam practice, and also gets used (for example) in 
wifi captive portals.


On 06/03/2013 03:36 PM, Ward, Mike S wrote:
> Hello all, I was trying to follow the thread on the NXDOMAIN and got lost. :) I have a question about using forwarders. If the DNS that is using forwarders receives a query for a zone it's not authoritative for even if it's in the same network, does it go to the forwarders for zone information? I'm trying to get my head around what was discussed in the NXDOMAIN thread. What makes a DNS authoritative for a zone?
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