DNS Configuration on linux.

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