This section outlines the necessary settings for using DNS through the LWRESD resolver instance. The configuration differs depending on whether the Light-Weight Resolver Daemon (LWRESD) is accessible locally or remotely under BS2000 or another platform.
Starting LWRESD
By default, LWRESD starts implicitly with the standard configuration file during DCSTART (/DCSTART or /DCOPT with LWRESD=*YES). Alternatively, LWRESD can be started after BCAM using the START-LWRESD command.
Note:
If DNS is not being used or LWRESD is running remotely, starting LWRESD is not mandatory (/DCSTART or /DCOPT with LWRESD=*NO). However, it is recommended to have LWRESD running on the system to avoid unwanted timeout delays during name resolution (e.g., for the FTP server).
Configuring LWRESD
Configuration file: SYSDAT.LWRESD.nnn.RESOLV.CONF
At least one accessible and functional DNS server must be entered and the domains to be used should be included. A detailed description of LWRESD and its settings can be found in chapter "DNS Resolver connection".
Note:
When LWRESD is reachable remotely, an entry in the LWRESD configuration file is not strictly necessary but advisable. This way, when using DIG and NSLOOKUP, no server specification is required.
Ensure accessibility of the DNS servers
To ensure LWRESD can contact the DNS servers listed in its configuration file, there must be a working connection to all DNS servers. This can be managed via Automatic End-System Inclusion (AEC) with appropriate entries in a system file (see the chapter "Automatic end system creation") or through manual definitions (see the chapter "Dynamic generation with BCAM commands").
Enable LWRESD server (LWRESD remote)
When using LWRESD remotely, the IP/IPv6 address and port of LWRESD (if different from the standard port) must be enabled for BCAM using the MODIFY-DNS-ACCESS command (operand DNS-RESOLVER). If the LWRESD server also runs on BS2000, these entries must be made on that host as well.
Allow DNS use
The use of the Domain Name System (via LWRESD) must be explicitly activated in BCAM:
/MODIFY-BCAM-OPTIONS DNS-OPTIONS=*PARAMETERS(DNS-USAGE=*ON)
You can use /SHOW-DNS-ACCESS to display the current settings.
Note:
This setting applies only to DNS usage by BCAM during AEC, not to DNS usage by Sockets applications on the system.
Restrictions on DNS access
With the /MODIFY-DNS-ACCESS command, you can restrict DNS access, specifically AEC via DNS, for certain IP/IPv6 addresses or BCAM names. Detailed information about this command and its settings can be found in the section "MODIFY-DNS-ACCESS".