Chapter 4 - Lab

1
Chapter 4 - Lab

• DNS Configuration in Linux

2
Lab Projects

• 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

Objective Upon completion you must show using
the dig command you get the correct IP and
corresponding domain name!
3
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

4
DNS Configuration in LinuxFile Structure
Client DNS Configuration
Server DNS Configuration

• Adding nameserver and domain
• Nameserver Corresponding IP address
• Domain Corresponding domain name

• Name resolution

5
Server DNS Configuration in LinuxFile Structure
1- Configure this file so it reads the proper
lookup files below
File name
/etc/named.conf
Defines other subdomains such as research.technow
idgets.com. mail.technowidgets.com.
Defines other subdomains such as web1 192.168.0.
20 research 192.168.0.150 mail 192.168.0.200
2- Create these two files for both forward and
reverse lookup files
6
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.0.168.192

7
/etc/named.confCreating a DNS for the
technowidgets.com domain

• Default setup is for localhost 127.0.0.1
• 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

8
/etc/named.conf

• Also, we can add the following line
• zone 0.168.192.in-addr.arpa IN
• type master
• file named.0.168.192
• The domain begins at IN-ADDR.ARPA and has a
  substructure which follows the Internet
  addressing structure
• Example data for Internet address 10.2.0.52 is
  located at domain name 52.0.2.10.IN-ADDR.ARPA
• This allows for reverse lookup for the domain
• It uses all or part of the 192.168.0.20 network

Make sure 192.168.0.20 matches your hard drive
number!
9
/var/named.technowidgets.com File ContentMust be
typed!

• TTL 86400
• _at_ IN SOA web1.technowidgets.com.
  admn.technowidgets.com. (
• 2002072100
  Serial
• 28800
  Refresh
• 14400
  Retry
• 3600000
  Expire
• 86400 )
  Minimum
• IN NS web1
• IN A 192.168.0.20
• IN MX 10 mail.technowidgets.com.
• web1 IN A 192.168.0. 20
• www IN CNAME web1
• research IN A 192.168.0.150
• IN MX 10 mail
• mail IN A 192.168.0.200

10
named.0.168.192 File Content Must be typed!

• TTL 86400
• _at_ IN SOA web1.technowidgets.com.
  admn.technowidgets.com. (
• 2002072100
  Serial
• 28800
  Refresh
• 14400
  Retry
• 3600000
  Expire
• 86400 )
  Minimum
• IN NS web1
• 20 IN PTR web1.technowidgets.com.
• 150 IN PTR research.technowidgets.com.
• 200 IN PTR mail.technowidgets.com.

11
Starting DNS in LinuxUseful 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

12
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 192.168.0.20 ? Your HD!
• nameserver 192.168.0.20
• The following line associates this computer with
  the technowidgets.com domain
• domain technowidgets.com

13
Troubleshooting DNSdig available on Linux
Use dig command to check the results!
Upon Completion you must be able to get
this! -- Must match your HD!
14
Troubleshooting DNS

• Linux
• dig hostname.com
• dig silent 192-168-0-xx
• ping

• Windows
• nslookup hostname.com
• nslookup x 192-168.0.xx
• Ipconfig
• ping

15
References

• For Linux
• http//www.siliconvalleyccie.com/linux-hn/dns-stat
  ic.htm
• For windows
• http//www.microsoft.com/technet/prodtechnol/windo
  wsserver2003/library/ServerHelp/5fe46cef-db12-4b78
  -94d2-2a0b62a28271.mspx
• Read about IN-ADDR.ARPA domain
• http//www.freesoft.org/CIE/RFC/1035/36.htm