CIS 192B – Lesson 2 Domain Name System

CIS 192B – Lesson 2 Types of Services Infrastructure –DHCP, DNS, NIS, AD, TIME Intranet –SSH, NFS, SAMBA Internet –MAIL, WEB, FTP, CUPS

CIS 192B – Lesson 2 Components of a Service / etcusr var sysconfig init.dbin lib sbin log

CIS 192B – Lesson 2 An Overview Created in 1983 from the work led by Paul Mockapetris Improves the deficiencies of the /etc/hosts file DNS manages two databases (zones)  Forward lookup zones: for mapping Domain names to IP addresses  Reverse lookup zones: for mapping IP addresses to Domain names Three components to DNS:  Resolver  The Server  Primary  Secondary  Caching  Database files (db.domain-name) Supports two type of queries:  Recursive  Iterative Most popular implementation of DNS is Berkely Internet Name Daemon (BIND) Maintained by the Internet Software Consortium:

CIS 192B – Lesson 2 DNS Service Installation Package names: bind, caching-nameserver, [bind-chroot] Daemon name: /usr/sbin/named Startup script: /etc/rc.d/init.d/named start or service named start Database files: /var/named/named.ca IP address of root servers /var/named/db.in-addr.arpa reverse lookups /var/named/db.domain-name forward lookups Configuration files: /etc/named.conf /etc/resolv.conf /etc/nsswitch.conf To reload configuration files: rndc reload

CIS 192B – Lesson 2 Steps to Installation 1.Install software package using yum or rpm 2.Customize service’s configuration file 3.Modify the firewall to allow access to the service 4.Configure service to automatically start when system boots 5.Monitor and verify service is running 6.Troubleshoot as necessary 7.Monitor log files as appropriate 8.Configure additional security

CIS 192B – Lesson 2 named.conf

CIS 192B – Lesson 2 Syntax Sections: name { directives... }; Address Match Lists: { ! ; /24; }; { /24; 10.10/16; ; }; Zones: zone “zone-name” { type [master | slave] file db.zone-name };

CIS 192B – Lesson 2 Database Zone files $TTL ; domain Zone SOA hostname.fqdn. root.fqdn. ( ; serial number 10800; refresh (sec) 1800; retry ; expire 300 ); minimum IN NS hostname.gqdn. hostnameIN Aip-address alias IN CNAMEhostname

CIS 192B – Lesson 2 Database Resource Records SOAStart of Authority NSNameserver MX Mail hubs A Address CNAMEAliases PTRPointer (for reverse lookups)

CIS 192B – Lesson 2 Network Diagrams

CIS 192B – Lesson 2 Network Diagrams

CIS 192B – Lesson 2 Project Diagram 1 Roter Router/Firewall Roter /24 NoPar Internet X.0/24 DNS DHCP NFS Mail CUPS SSH Server1 Server2 Client1

CIS 192B – Lesson 2 Project Diagram 2 Roter Router/Firewall NoPar / X.0/ Y.0/24 Roter ClientServer NFS SSH DHCP Server Mail DNS Server HTTP FTP Internet

CIS 192B – Lesson 2 Project Diagram 3 Roter Router/Firewall NoPar /24 Internet Roter Router/Firewall Roter Server CUPS DNS Roter Server1 DHCP NFS Roter Server2 SSH DNS