This document discusses DNS configuration. It provides an overview of DNS and its history. It describes DNS name space and how it works with an inverted tree structure. It discusses DNS name servers and zones, including forward and reverse lookup zones. It outlines the steps to configure DNS on a server, which includes installing bind9, editing configuration files for zones, and restarting the bind9 service. Tests are done using nslookup to resolve names and addresses.

1. DNS CONFIGARATION
SUBMITTED BY:
Vinod Gour

2. CONTENTS:
 Overview
 History
 DNS-Name Space & Working
 Example of DNS Name Space
 DNS-Name Server
 DNS-Zone
 DNS-Configuration

3. DNS-Overview
 Domain Name System (DNS) is a database system
that translates a computer's fully qualified domain
name into an IP address.
 For example Domain name www.amazon.com
corresponding to IP address (207.171.166.48).
 DNS serves as an electronic telephone book for a
computer network.

4. HISTORY OF DNS
 In 1967, DNS did not exist.
 in 1971, Peggy Karp conceived of “host mnemonics” (RFC
226) and develop “HOSTS.txt”
 The first version of this file was distributed in 1972.
 The Domain Name System was conceived in RFC 799 in
1981 Written by Dr. David Mills.
 In 1987, the publication of RFC 1034 and RFC 1035 updated
the DNS specification.

5. DNS –Name Space & Working
 The namespace refers to the hierarchical layout of DNS
names
 the DNS namespace is laid out in an inverted tree.
 At the top of the DNS namespace is the "Root" defined
by null character
 The root is not normally explicitly specified in user
applications but when specified is denoted by a trailing
period(www.vtc.com)

6. DNS –Name Space & Working
 Below the root in the DNS namespace, are the top
level domains or TLDs.
 These TLDS are maintained by the Internet
corporation for assigned names and numbers, or
ICAN, for Internet use
 On a private network you can use any TLD you
want but it is bad practice in case you ever connect
your network to the internet.

7. DNS –Name Space & Working
 The remainder of the namespace is open for use
 You can register domain names beneath several of
the TLDs

8. An Example of Name-Space

9. DNS-Name Server
 A Server which handles DNS-Queries called
“Name-Server”.
 This server hold a list of all the IP addresses within its
network and a cache of IP addresses.
 When your computer requests an IP address, one of
three things happens.

10. DNS-Name Server
 If the requested IP address is registered locally.
 If the requested IP address is not registered locally ,but
someone within your organization has recently
requested the same IP address.
 If the requested IP address is not registered locally, and
you are the first person to request information about
this system in a certain period of time.

11. DNS ZONES
 Every domain name, which is a part of the DNS
system, has several DNS settings, also known as DNS
records. In order for these DNS records to be kept in
order, the DNS zone was created.
 Their are 2 types of zones:
1) A forward lookup zone
2) A reverse lookup zone

12. DNS ZONES
 A forward lookup zone is a DNS zone in which
hostname to IP address relations are stored. When a
computer requests the IP address of a specific
hostname, the forward lookup zone is queried and the
result is returned.
 A reverse lookup zone does just the opposite. When a
computer requests the hostname of an IP address, the
reverse lookup zone is queried and the result is
returned.

14. STEPS
It involves following steps:-
 sudo su
 nano /etc/network/interfaces – for static IP.
 /etc/init.d/networking restart
 ifconfig
 apt-get install bind9
 nano /etc/bind/named.conf.local
 nano /etc/bind/db.up.omg (forward lookup zone)
 nano /etc/bind/db.192 (reverse lookup zone)
 nano /etc/resolv.conf
 /etc/init.d/bind9 restart
 nslookup sgsits.up.omg & nslookup 192.168.1.3

15. Step 1 : nano /etc/network/interfaces – for static IP

16. Step 2 : /etc/init.d/networking restart

17. Step 3 : ifconfig - Our DNS Server has now a static IP

18. Bind9
 BIND (Berkeley Internet Name Domain) is an
implementation of the DNS protocols and provides an
openly redistributable reference implementation of the
major components of the Domain Name System.
 BIND9 is latest version of BIND architecture.
 features of BIND9 : are DNS Security, IPv6,DNS
Protocol Enhancements, Views, Multiprocessor
Support, and an Improved Portability Architecture.

19. Step 4 : apt-get install bind9

20. Step 5 : nano /etc/bind/named.conf.locals

21. Step 6: nano /etc/bind/db.up.omg

22.  A(Address):points our domain to an ip address.
 AAAA: same as A record.
 CNAME(Canonical name): this record points our
sub-domain to another domain name
 MX(Mail exchanger): MX records control where our
emails are received.
DNS ZONE RECORDS

23.  PTR(Pointer): defines what name will be called when
an IP address is looked up.
 TXT: The TXT records are custom records which
contain machine-readable data.
 NS: identify the names of the DNS servers.
DNS ZONE RECORDS

24. Step 6 : nano /etc/bind/db.up.omg

25. Step 7 : nano /etc/bind/db.192

26. Step 8 : nano /etc/resolv.conf

27. Step 9 : /etc/init.d/bind9 restart

28. Step 11 : nslookup sgsits.up.omg & nslookup 192.168.1.3