28.1. DNS Resource

28.1. DNS Resource
	Chapter 28. DNS - Domain Name System

The Abilis CPX DNS resource may behave as a DNS Resolver, as a DNS Relay or as a DNS Server too.

28.1.1. Activating the DNS resource

Add the resource to the Abilis system with the following command.

[12:18:28] ABILIS_CPX:a res:dns

RES:DNS ALREADY EXISTS

The DNS resource may already exist in the system, but may not yet be active: set it active with the command:

[12:18:31] ABILIS_CPX:s act res:dns

COMMAND EXECUTED

	Caution
	After adding or setting the DNS active, you must restart the Abilis to make the resource running (use the command warm start to reboot the Abilis).

[17:14:59] ABILIS_CPX:s p dns act:yes

COMMAND EXECUTED

[17:15:17] ABILIS_CPX:d p dns

RES:Dns -----------------------------------------------------------------------
Run    DESCR:Domain_Name_System
       LOG:NO           ACT:YES 
       udp-locport:53   SRCADD:OUT-IP                      TOS:0-N      
       wdir:C:\APP\DNS\
       - Resolver -------------------------------------------------------------
       SERVERS:AUTO
       PRIMARY:#                 SECONDARY:#
       DELAY:5                   RTY:1                    
       CACHE:YES                 cache-size:500
       - Relay/Server ---------------------------------------------------------
       RELAY:NO                  relay-size:500            RELAY-TOUT:10  
       RELAY-BLACKLIST:YES       RELAY-BLACKLIST-BYPASS:#
       SERVER:NO
       IPSRC:*                   IPSRCLIST:#

28.1.2. DNS resource parameters

Use the following command to display the parameters of the resource; the command d p dns ? displays the meaning of all parameters.

[12:18:35] ABILIS_CPX:d p dns

RES:Dns -----------------------------------------------------------------------
Run    DESCR:Domain_Name_System
       LOG:NO           ACT:YES 
       udp-locport:53   SRCADD:OUT-IP                      TOS:0-N      
       wdir:C:\APP\DNS\
       - Resolver -------------------------------------------------------------
       SERVERS:AUTO
       PRIMARY:#                 SECONDARY:#
       DELAY:5                   RTY:1                    
       CACHE:YES                 cache-size:500
       - Relay/Server ---------------------------------------------------------
       RELAY:NO                  relay-size:500            RELAY-TOUT:10  
       RELAY-BLACKLIST:YES       RELAY-BLACKLIST-BYPASS:#
       SERVER:NO
       IPSRC:*                   IPSRCLIST:#

Meaning of the most important parameters:

LOG: Logging functionalities activation/deactivation.
ACT: Runtime DNS activation/deactivation.
SRCADD: Sets the IP address to be set in every outgoing DNS request.
TOS: Sets the TOS value for DNS service;
SERVERS: Servers IP resource [AUTO, Ip-nnn, STATIC], where 'nnn' is an IP resource index [1..250]. [AUTO: DNS resolver uses the servers retrieved by an IP resources that negotiates them e.g. IP-PPP. DNS: parameter of IP resources must be set to RETRIEVE, Ip-nnn: DSN resolver uses the available servers through Ip-nnn resource, STATIC: DNS resolver uses PRIMARY and SECONDARY servers].
PRIMARY: Sets the IP address of the primary DNS server, which the Abilis CPX resource refers to for name resolution.
SECONDARY: Sets the IP address of the secondary DNS server, which the Abilis CPX port refers to for name resolution.
DELAY: Sets the maximum time (in seconds) to wait for a response from the DNS server.
RTY: Sets how many times a request has to be sent to the DNS server if the DNS Resolver doesn't get any response in the expected time interval fixed in the DELAY parameter.
CACHE: Activates/deactivates the DNS cache.
cache-size: Sets the maximum size of the cache (expressed in bytes).
RELAY: Activates/deactivates the DNS Relay feature for DNS resource. DNS relay allows the relay of external DNS requests of DNS clients from CPX to DNS server.
relay-size: Sets the maximum size of the relay table (expressed in bytes).
RELAY-TOUT: Sets the time of life (in seconds) for a record in DNS relay table.
RELAY-BLACKLIST: Enable/disable DNS Relay blacklist service [NO, YES]
RELAY-BLACKLIST-BYPASS: List of IP adresses that bypass Relay blacklist service [ListName, #]
SERVER: Activates/deactivates the DNS Server feature for DNS resource.
IPSRC: Selects the IP address of the client from which the requests will be accepted.
IPSRCLIST: Sets the list of DNS Client systems enabled to use the DNS Relay or Server services.

The following command allows the administrator to change the configuration of the resource:

s p dns parameter:value...

	Caution
	To activate the changes made on the upper case parameters, execute the initialization command init res:dns; while to set act the changes made on the lowercase parameters a save conf and an Abilis restart are required (i.e. with warm start command).