# ENUM Query
### Introduction
Starting with release 3.1, it is possible to issue ENUM Query requests to DNS servers from routing scripts. To do so, the params\[:enum\_query] object must be filled with the required ENUM Query attributes params\[:enum\_query]\[:fqdn] and [an exception must be raised](/configuration-details/configuration-by-web-portal-category/routing-scripts/development-guides-and-tutorials/enum-query.md) with reason :enum\_query\_required.
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When ENUM Query completes, the routing script is called again with the result. The params\[:enum\_query] object will be filled with the ENUM Query attributes from the response. The params\[:enum\_query]\[:result] field will also contain a string indicating the result of the ENUM Query:
* *ok*: The ENUM Query was successful.
* *timeout*: The ENUM Query was not answered.
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The params\[:enum\_query]\[:responses\_list] field will contain a list of hash responses for each NAPTR records.
NAPTR records contain:
* *:uri*
* *:order*
* *:preference*
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Example:
***
> params\[:enum\_query]\[:responses\_list] \[{:order=>"200", :preference=>"10", :uri=>"!^03111.\*$!!"}, {:order=>"100", :preference=>"1", :uri=>"!^03222.\*$!!"}, {:order=>"200", :preference=>"1", :uri=>"!^03111.\*$!!"}]
***
Using enum\_called\_remap.rb before filter script allows handling of ENUM query requests/responses. The match and replace regular expression from ENUM query responses are applied to params\[:call]\[:called] to get "new called". This script allows update of the call parameters according to "new called" value. Refer to enum\_called\_remap.rb before filter script to get instructions on how to integrate this script into the main routing script (i.e. simple\_routing\_sbc.rb):
***
> ... require 'enum\_called\_remap' unless defined?(EnumCalledRemap) ... include EnumCalledRemap ... before\_filter :method => :enum\_called\_remap ...
***
### Resolve ENUM Query down to type A records
The ENUM query could also resolve uri from responses and get matching outgoing NAP, NAP proxy IP and port through a sequence of DNS queries (i.e. NAPTR, SRV down to type A records). This behavior could be requested using "dns\_query" parameter:
***
> params\[:enum\_query]\[:dns\_query] = true
***
When ENUM and DNS Queries complete, the routing script is called again with the results. The params\[:enum\_query] and params\[:dns\_query] objects will be filled with the ENUM Query and the DNS Query attributes from the responses. The DNS query responses are available through params\[:dns\_query]\[:responses\_list] call parameters:
***
> params\[:dns\_query]\[:responses\_list] \[{:nap=>"NAP\_UDP", :nap\_proxy\_ip=>"10.3.14.191", :nap\_proxy\_port=>"8080", :transport=>"UDP", :order=>"100", :preference=>"1", :priority=>"0", :weight=>"5"}, {:nap=>"NAP\_TCP", :nap\_proxy\_ip=>"10.3.14.192", :nap\_proxy\_port=>"8081", :transport=>"TCP", :order=>"100", :preference=>"2", :priority=>"1", :weight=>"10"}]
***
### Add dynamic routes
The ENUM query could also add dynamic routes base on DNS query responses. This could be requested using the "add\_dynamic\_routes" call parameter:
***
> params\[:enum\_query]\[:dns\_query] = true params\[:enum\_query]\[:add\_dynamic\_routes] = true
***
Note that it is mandatary to send DNS query to add dynamic routes.
The "base\_routing.rb" script version should be greater then 1.37 in order to allow dynamic routes creation base on DNS query responses.
When requesting to add\_dynamic\_routes, the dns\_query responses are used to create routes. Make sure that your configuration includes a route with remapped\_nap = "Registered or DNS users". A route will be created for each DNS query responses. The routes "remapped\_nap" takes NAP value from DNS query responses.
It is required to modify main routing script (i.e. simple\_routing\_sbc.rb) to forward IP/port values from params\[:routes] to params\[:call] like we are doing for NAP. See following example:
> ***
>
> ...
>
> \# This will select the outgoing NAP for this call according to the "remapped\_nap" route parameter route\_remap :call\_field\_name => :nap, :route\_field\_name => :remapped\_nap
>
> \# This will select the outgoing NAP proxy ip address for this call according to the "remapped\_nap\_proxy\_ip" route parameter route\_remap :call\_field\_name => :nap\_proxy\_ip, :route\_field\_name => :remapped\_nap\_proxy\_ip
>
> \# This will select the outgoing NAP proxy port for this call according to the "remapped\_nap\_proxy\_port" route parameter route\_remap :call\_field\_name => :nap\_proxy\_port, :route\_field\_name => :remapped\_nap\_proxy\_port ...
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