Page 174 - DCAP106_OPERATING_SYSTEM_TOOLS

Unit 10: Servers

used HTTP-server in the world today. It surpasses all free and commercial competitors on the Notes
market, and provides a myriad of features; more than the nearest competitor could give you on
a UNIX variant. Dynamic Host Configuration Protocol (DHCP) repeatedly assigns IP addresses
and other network configuration information (subnetmask, broadcast address, etc.) to computers
on a network. DNS acts as a directory service for all of these systems and let you to specify each
one by its hostname.

10.1 DNS Server

As a service, DNS is crucial to the operation of the Internet. When you enter www.some-domain.
com in a Web browser, it’s DNS that takes the www host name and translates it to an IP address.
Without DNS, you could be connected to the Internet just fine, but you ain’t goin’ no where. Not
unless you keep a record of the IP addresses of all of the resources you access on the Internet and
use those instead of host/domain names.

So when you visit a Web site, you are in fact doing so using the site’s IP address even though
you specified a host and domain name in the URL. In the background your computer quickly
queried a DNS server to get the IP address that corresponds to the Web site’s server and domain
names. Now you know why you have to specify one or two DNS server IP addresses in the TCP/
IP configuration on your desktop PC (in the resolv.conf file on a Linux system and the TCP/IP
properties in the Network Control Panel on Windows systems).

10.1.1 Configuring DNS Server

Domain Name System (DNS) converts the name of a Web site.

Example: Domain name system converts (www.Ignou.ac.in) to an IP address
(220.227.168.115).
This step is significant, because the IP address of a Web site’s server, not the Web site’s name, is
used in routing traffic over the Internet.
DNS Domains

Every person in the world has a first name and a last, or family, name. The same thing is true in
the DNS world: A family of Web sites can be loosely described a domain.

Example: The domain Ignou.ac.in has a number of children, such as www.Ignou.ac.in
and mail.Ignou.ac.in for the Web and mail servers, respectively.

BIND
BIND is an acronym for the Berkeley Internet Name Domain project, which is a group that
sustains the DNS-related software suite that runs under Linux. The most well known program in
BIND is named, the daemon that responds to DNS queries from remote machines.
DNS Clients

A DNS client doesn’t store DNS information; it has to refer to a DNS server to get it. The only
DNS configuration file for a DNS client is the /etc/resolv.conf file, which defines the IP address
of the DNS server it should use. You shouldn’t need to configure any other files. You’ll become
well acquainted with the /etc/resolv.conf file soon.

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