DNS
• Domain Name System
– name servers
– Translates FDQN to IP address
• List of fully qualified domain names (FDQN) and
their IP addresses,
• FDQN has three or more segments
– first segment is host the rest of the segments are for the
network in which the host is located
» www.ivc.edu
» www.ivc.cc.ca.us
• Manual Translation
– /etc/hosts
Domains
• Internet is composed of many domains
• Each domain needs a DNS server to keep track
of the FDQN and IP address on it’s network
• The section that the DNS is responsible for is
called a zone
• One domain may corresponded to a domain,
many zones may be within a domain each with
its on name server
– i.e. .gov .com .edu .net
• DNS operation:
– Client request connection to remote host by
entering a FDQN, the DNS server responds
with the corresponding IP address, the client
then connects to remote host by IP address
• DNS Client
– The name of the DNS servers that service a
host network are kept in /etc/resolv.conf
• Usually specified when setting up the network
connection.
BIND
• Berkeley Internet Name Domain
– Developed at Cal. Berkeley
– Maintained by Internet Software Consortium
(ISC) www.isc.org
• Local documentation:
– /usr/share/doc/bind-9.4..0
– /usr/share/doc/bind-9.4.0/arm/Bv9ARM.html
• Documentation and tools
– www.dns.net/dnsrd
Servers and Tools
• BIND DNS software
– name server daemon ( named )
• rndc tool can be used to manage
– sample configuration files
– resolver libraries
• Tools
– dig and nslookup test basic operation of named ( DNS )
– named-checkconfig
• Checks syntax of DNS configuration file ( named.conf )
– named-checkzone
• Checks syntax of zone file
– GUI system-config-bind
Starting and Stopping
• service named start
– stop, restart, status
• chkconfig named on
Configuration
• configuration file
– named.conf
• zone files
– defined in named.conf
– IP to FDQN association
– Types
• Master, Slave, Forward, IN-ADDR.ARPA, Hint
• cache file
Server Types
• Master Server
• Slave Server
• Forwarder Server
• Caching only server
• Stealth server
Location of BIND files
/var/named/chroot
– chroot directory sets up a chroot jail, a virtual
root directory for users of the DNS service
• documentation www.tldp.org
• Configuration Files
– /var/named/chroot/etc/named.conf
– /var/named/chroot/var/named/*
• zones
• named.conf
– consists of BIND statements with attached
blocks within which specific options are listed
• Reference Page 836 and 837
• Zone files
– hold domain name information about hosts in
resource records
• takes up one line but can be extended by using
parentheses to use several lines usually the case
with a SOA record
• name [] [] []
system-config-bind