Chapter 4 - Lab DNS Configuration in Linux

 DNS Configuration in Linux Projects 4-1 through 4-3 Projects 4-4 deals with multiple domains  DNS Configuration in Windows Projects 4-5 through 4-8 Projects 4-9 deals with multiple domains Lab Projects Objective: Upon completion you must show using the dig command you get the correct IP and corresponding domain name!

Review of Zoning  A zone is a part of the domain namespace  For a domain as small as technowidgets.com, the domain name represents a single zone  For large organizations (such as IBM), subdomains can be divided into separately maintained zones Each zone typically has a separate DNS  Zone file configuration Forward Lookup  These zones contain entries that map names to IP addresses Reverse Lookup  These zones contain entries that map IP addresses to names

DNS Configuration in Linux File Structure /etc/named.conf File name: /etc/resolve.conf File name: Client DNS ConfigurationServer DNS Configuration  Adding nameserver and domain Nameserver: Corresponding IP address Domain: Corresponding domain name  Name resolution

Server DNS Configuration in Linux File Structure Forward Lookup file /var/named/ named.technowidgets.com Reverse Lookup File /var/named/ named /etc/named.conf File name: 1- Configure this file so it reads the proper lookup files below 2- Create these two files for both forward and reverse lookup files Defines other subdomains such as: research.technowidgets.com. mail.technowidgets.com. Defines other subdomains such as: web research mail

DNS Configuration in Linux  /etc/named.conf describes the files that configure the zones  There are two primary files that it describes Forward lookup is described by named.technowidgets.com Reverse lookup is described by named

/etc/named.conf Creating a DNS for the technowidgets.com domain  Default setup is for localhost This is shown in figure 4-7  In named.conf add the following line zone "technowidgets.com" { type master; file “named.technowidgets.com”; };  This allows technowidgets.com to be resolved by /var/named/named.technowidgets.com  There can be multiple domains in a single named.conf file

/etc/named.conf  Also, we can add the following line zone “ in-addr.arpa” IN { type master; file “named ”; };  The domain begins at IN-ADDR.ARPA and has a substructure which follows the Internet addressing structure Example: data for Internet address is located at domain name IN-ADDR.ARPA  This allows for reverse lookup for the domain  It uses all or part of the network Make sure matches your hard drive number!

/var/named.technowidgets.com File Content Must be typed! IN SOA web1.technowidgets.com. admn.technowidgets.com. ( ; Serial ; Refresh ; Retry ; Expire ) ; Minimum IN NS web1 IN A IN MX 10 mail.technowidgets.com. web1 INA www INCNAMEweb1 research INA INMX 10mail mail INA

named File Content Must be typed! IN SOA web1.technowidgets.com. admn.technowidgets.com. ( ; Serial ; Refresh ; Retry ; Expire ) ; Minimum IN NS web1 20 IN PTR web1.technowidgets.com. 150IN PTR research.technowidgets.com. 200IN PTR mail.technowidgets.com.

Starting DNS in Linux Useful commands  To start DNS /etc/rc.d/init.d/named start  To restart DNS /etc/rc.d/init.d/named restart  To stop DNS /etc/rc.d/init.d/named stop  To make DNS start when you boot Linux Add the above commands to start DNS to /etc/rc.d/rc.local

Configuring Client DNS in Linux  Objective: How IP addresses are corresponding to domain names Modify /etc/resolv.config The following line directs the client to use the DNS server at  Your HD!  nameserver The following line associates this computer with the technowidgets.com domain  domain technowidgets.com

Troubleshooting DNS dig – available on Linux Upon Completion; you must be able to get this! -- Must match your HD! Use dig command to check the results!

Troubleshooting DNS  Linux dig hostname.com dig –silent xx ping  Windows nslookup hostname.com nslookup –x xx Ipconfig ping

References:  For Linux:  For windows /5fe46cef-db12-4b78-94d2-2a0b62a28271.mspx /5fe46cef-db12-4b78-94d2-2a0b62a28271.mspx  Read about IN-ADDR.ARPA domain