recursion vs allow-recursion

[Smith, William E. (Bill), Jr.]

Per the BIND ARM, the default is indeed yes.  I've included that bit of
text from the ARM for convenience.

recursion
If yes, and a DNS query requests recursion, then the server will attempt
to do all the work required
to answer the query. If recursion is off and the server does not already
know the answer, it will
return a referral response. The default is yes. Note that setting
recursion no; does not prevent
clients from getting data from the server's cache; it only prevents new
data from being cached as an
effect of client queries. Caching may still occur as an effect the
server's internal operation, such as
NOTIFY address lookups. See also fetch-glue above. 

As for the second question, I believe the answer is no -- you simply
don't include the recursion option in your named.conf, thus assuming the
default.  If you enable it to no, I believe that trumps anything in
allow-recursion.

As for the interaction between the 2 options, the former controls
whether the server will perform recursive queries on behalf of clients
sending them while the latter restricts who can make said queries if
recursion is enabled.

If you have a copy of the BIND ARM handy, it does a pretty good job of
explaining things.

Bill Smith 
<mailto:bill.smith at jhuapl.edu> 
ISS Server Systems Group 
Johns Hopkins University Applied Physics Laboratory 
11100 Johns Hopkins Road 
Laurel, MD 20723 
Phone:  443-778-5523 
Web:  http://www.jhuapl.edu    



-----Original Message-----
From: bind-users-bounce at isc.org [mailto:bind-users-bounce at isc.org] On
Behalf Of Barry Finkel
Sent: Wednesday, March 08, 2006 11:10 AM
To: bind-users at isc.org
Subject: recursion vs allow-recursion

I see in the "options" statement in the config file two items:

      recursion yes_or_no;
      allow-recursion { address_match_list }; 

I assume that the default for the first is yes.  If I want to add the
second statement with an address_match_list, do I have to set

     recursion no;

in addition?  How do these two statements iteract?  Thanks.
----------------------------------------------------------------------
Barry S. Finkel
Computing and Information Systems Division
Argonne National Laboratory          Phone:    +1 (630) 252-7277
9700 South Cass Avenue               Facsimile:+1 (630) 252-4601
Building 222, Room D209              Internet: BSFinkel at anl.gov
Argonne, IL   60439-4828             IBMMAIL:  I1004994