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 » » 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) Local documentation: –/usr/share/doc/bind –/usr/share/doc/bind-9.4.0/arm/Bv9ARM.html Documentation and tools –

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 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 [ ] [ ] [ ]

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