Red Hat Enterprise Linux 5 Administration Unleashed

CHAPTER 16Hostname Resolutionwith BINDIN THIS CHAPTER. Understanding DNS Concepts. Allowing Connections. Configuring BIND. Configuring BIND Graphically. Logging ConnectionsEvery computer on a network, whether it be a public-facingsystem on the Internet or one only accessible from an internalnetwork, has a series of numbers called an IP address thatidentifies it to all other systems on the network. Eachcomputer on the network must have a unique IP address.To make it easier to remember and identify systems, eachIP address can be resolved to a hostname such asserver.example.com, which must also be unique pernetwork. IP addresses can be translated, or resolved, to hostnames,and vice versa, via the Internet Domain NameSystem, or DNS. DNS is a set of distributed databases with ahierarchy that dictates which server is more authoritativefor a particular set of systems.To set up a DNS server, also referred to as a name server, onRed Hat Enterprise Linux, use BIND (Berkeley InternetName Domain). This chapter first explains the basics ofhow DNS works. Then, it guides you through configurationof Red Hat Enterprise Linux as a DNS server using BIND.Understanding DNS ConceptsA DNS server, or name server, is used to resolve an IP addressto a hostname or vice versa. Before configuring BIND tocreate a DNS server, you must understand some basic DNSconcepts.When talking to another person, you usually refer to himby his first name even though he has a surname and sometimesa middle name as well. Similarly, administratorsoften refer to systems by the first part of their hostnamessuch as talon for talon.example.com. The entire hostnamewith its domain such as talon.example.com is called a fullyqualified domain name (FQDN). The right-most part of the