Hi,
For use CIDR, first of all you have to configure the lookup with this kind of match
http://docs.splunk.com/Documentation/Splunk/6.4.0/Admin/Transformsconf
> match_type = <string>
> * A comma and space-delimited list of <match_type>(<field_name>)
> specification to allow for non-exact
> matching
> * The available match_type values are WILDCARD, CIDR, and EXACT. EXACT is
> the default and does not need to be
> specified. Only fields that should
> use WILDCARD or CIDR matching should
> be specified in this list
After you do that, you can use your lookup as you want.
Hope i help you
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