LPI Linux Certification/Basic DNS Server Configuration

Detailed Objectives (207.1) (LPIC-2 Version 4.5) Weight: 3 Description: Candidates should be able to configure BIND to function as a caching-only DNS server. This objective includes the ability to manage a running server and configuring logging. Key Knowledge Areas: BIND 9.x configuration files, terms and utilities. Defining the location of the BIND zone files in BIND configuration files. Reloading modified configuration and zone files. Awareness of dnsmasq, djbdns and PowerDNS as alternate name servers. The following is a partial list of the used files, terms and utilities: /etc/named.conf /var/named/ /usr/sbin/rndc kill host dig Basic BIND 8 configuration Setting up a caching-only nameserver To speed up the cumbersome process of DNS queries, DNS servers usually cache answers from other DNS servers – even negative queries (i.e an authoritative server's answer « name does not exist » is also cached by your local DNS) Configuring BIND as a caching-only nameserver involves setting up only a « . » zone, that is, only tell it about the root nameservers and not specifying any zones, as follows : zone « . » in { type hint; file « named.cache »; }; The file named.cache can be generated by using dig @a.root-servers.net Logging in BIND is controlled by two main concepts : channels and categories A channel specifies where logged data goes : to syslog, to a file, etc... A category specifies what data is logged Channels allows you to filter messages by priority, like syslog's priorities. They are essentially the same, but two more are available for BIND : debug and dynamic, which affect debug level logging Debug sets a debug level, which will be active after the first trace command is given via ndc; dynamic will increment and decrement debug levels after each trace command is given via ndc Example of logging configuration: logging { channel my_syslog { syslog daemon; severity info; }; channel my_file { file « log.msgs »; severity dynamic; }; category statistics { my_syslog; my_file; }; category queries { my_file; }; }; To activate logging, after bind is started, issue a command : ndc trace Key terms, files and utilities : /etc/named.conf /usr/sbin/ndc /usr/sbin/named-bootconf Kill Exercises linux