The document describes how to set up a basic DNS server using Bind9 on Ubuntu. It explains DNS concepts like name resolution, zones, and domain space hierarchy. It then provides step-by-step instructions to install and configure Bind9, create forward and reverse lookup zones, check configurations, and test the DNS server.
This Presentation explains about Domain Name System Records and Their Usage.
This explains DNS Records to New Beginners in an accurate manner. Get to learn live technology in an enhanced way only at Hackveda
This Presentation explains about Domain Name System Records and Their Usage.
This explains DNS Records to New Beginners in an accurate manner. Get to learn live technology in an enhanced way only at Hackveda
The Domain Name System (DNS) is a hierarchical decentralized naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates more readily memorized domain names to the numerical IP addresses needed for the purpose of locating and identifying computer services and devices with the underlying network protocols. By providing a worldwide, distributed directory service, the Domain Name System is an essential component of the functionality of the Internet.
A complete Coverage of DNS and its features. This ppt deals with well balanced practical and theoretical aspects of DNS. The best ppt for a novice learner.
Overview of the Domain Name System (DNS).
In the early days of the Internet, hosts had a fixed IP address.
Reaching a host required to know its numeric IP address.
With the growing number of hosts this scheme became quickly awkward and difficult to use.
DNS was introduced to give hosts human readable names that would be translated into a numeric IP addresses on the fly when a requesting host tried to reach another host.
To facilitate a distributed administration of the domain names, a hierarchic scheme was introduced where responsibility to manage domain names is delegated to organizations which can further delegate management of sub-domains.
Due to its importance in the operation of the Internet, domain name servers are usually operated redundantly. The databases of both servers are periodically synchronized.
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The Domain Name System (DNS) is a hierarchical decentralized naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities. Most prominently, it translates more readily memorized domain names to the numerical IP addresses needed for the purpose of locating and identifying computer services and devices with the underlying network protocols. By providing a worldwide, distributed directory service, the Domain Name System is an essential component of the functionality of the Internet.
A complete Coverage of DNS and its features. This ppt deals with well balanced practical and theoretical aspects of DNS. The best ppt for a novice learner.
Overview of the Domain Name System (DNS).
In the early days of the Internet, hosts had a fixed IP address.
Reaching a host required to know its numeric IP address.
With the growing number of hosts this scheme became quickly awkward and difficult to use.
DNS was introduced to give hosts human readable names that would be translated into a numeric IP addresses on the fly when a requesting host tried to reach another host.
To facilitate a distributed administration of the domain names, a hierarchic scheme was introduced where responsibility to manage domain names is delegated to organizations which can further delegate management of sub-domains.
Due to its importance in the operation of the Internet, domain name servers are usually operated redundantly. The databases of both servers are periodically synchronized.
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DNS, which stands for domain name system, controls your domain name's website and email settings. When visitors go to your domain name, its DNS settings control which company's server it reaches out to.
DOMAIN NAME SYSTEM AND DYNAMIC DOMAIN NAME SYSTEM
Machines on the internet are identified by a unique IP address. But it is difficult for people to remember these addresses.
Humans are more comfortable with names rather than numbers. Hence it would be easier to identify a machine using a name instead of an address.
DDNS (Dynamic Domain Name System) allows us to overcome the issues related to Dynamic IP Addresses, in attempting to connect to a DVR somewhere on the Internet whose IP Address may change at any time.
The Domain Name System (DNS) is a hierarchical decentralized naming system that resolves Name to IP or vise versa.
DNS works with port no 53 (TCP and UDP )
For query resolving UDP protocol is used and for Zone transfer TCP port is used.
Install and Understand DNSSEC in Linux Server running BIND 9 with CHROOT JAIL system and Service.
By Utah Networxs
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Follow - @utah_networxs
2. DNS-Definition
Name Space
Flat Name Space
Hierarchial Name Space
Domain Name Space
FULLY QUALIFIED DOMAIN NAME
PARTIALLY QUALIFIED DOMAIN NAME
Distribution of Name Space
Hierarchy of Name servers
Zones and Domains
DNS in Internet
Resolution
DNS Messages
3. To identify an entity, TCP/IP uses IP address
which uniquely identifies connection of host
to internet.
We prefer to use names instead of numeric
address.
So we need a system that can map a name to
a numeric address and vice versa.This is
called DOMAIN NAME SYSTEM.
4. When internet was small, mapping was done
using HOST FILE which was stored on every
host.
Host file had only two columns:name and
address.
But now a days whole information is divided
into smaller parts and each part is stored in
different computer.This is called DNS.
5. The process of mapping a unique name with
a unique IP address.
FLAT NAME SPACE-
A name is assigned to an address and name
is a sequence of characters without structure.
It cannot be used in large system such as
Internet.
6. HIERACHICAL NAME SPACE-
• Each name is made of several parts.
• The first part can define the nature of
organization.
• Second part can define the name and third
can define the departments in organization.
• For example
o Smart.pu.edu
o Smart.unix.com
7. To have a hierarchical name space,a DOMAIN
NAME SPACE was designed.
In this design the names are defined in an
inverted tree structure with the root at top.
The tree can have only 128 levels i.e. level
0(root) to level 127.
Tree consists of nodes and each node has a
LABEL.
8.
9. Each node in the tree has a domain name.
Full domain name is sequence of labels
separated by dots(.)
Domain name is read from node up to root.
Always ends in a null label i.e. last character
is a dot.
10.
11. FULLY QUALIFIED DOMAIN NAME(FQDN)
It contains the full name of host.
A label is terminated by a null string.
Ex-cs.hmme.com.
PARTIALLY QUALIFIED DOMAIN NAME
It starts from a node but doesn’t reaches
root.
A label is not terminated by null string.
Ex-cs.hmme
12. Domain is a sub tree
of domain name space.
Each domain can be
divided into sub
domains.
13.
14. Region over which
server has the
responsibility and
authority.
Zone is a part of
entire tree.
Server can divide
domain into smaller
domains.
15. ROOT SERVER-IT is a server whose zone
consist of whole tree.These servers are
distributed all around the world.
PRIMARY SERVER-A primary server loads all
information from the local disk file.
SECONDARY SERVER-It transfers the complete
information from the primary server and it is
called Zone transfer.
16.
17.
18. Mapping a name to an address or an address to a
name is called-address resolution.
RESOLVER-It access the closest DNS server with a
mapping request.If the server has the
information, it satisfies the resolver ; otherwise
refers the resolver to other servers to provide the
information.
MAPPING NAMES TO ADDRESSES-Resolver gives
domain name to the server and ask for address.
19. MAPPING ADDRESS TO NAMES
Resolver sends IP address to the server to be
mapped to domain name.
This is called PTR or Inverse query.
Server uses inverse domain.
IP address-121.45.34.132
Domain name-132.34.45.121.in-addr.arpa.
20.
21.
22. CACHING
When a server asks for mapping from another
server and receive the response, it stores the
information an its cache memory before
sending it to the clients.
If the same or other client asks for the same
mapping,it can check its cache and resolve
the problem.
23.
24.
25. In DNS, when there is a change,such as
adding a new host,removing a host or
changing an IP address, change must be
made to the DNS master file.
Manual updating is not possible due to size
of Internet.
It is used to update DNS master file
automatically.
26. DNS can use either UDP or TCP.
PORT NO.53 is used by servers.
If size of response message is more than 512
bytes,TCP connection is used,otherwise UDP
is used.
29. sudo gedit /etc/bind/named.conf.options
Uncomment and edit the forwarders block.
write google’s dns server
8.8.8.8;
8.8.4.4;
Restart bind9 service.
sudo service bind9 restart.
Test using dig –x 127.0.0.1
30. DNS configuration files are stored
in /etc/bind directory. Primary configuration file
is/etc/bind/named.conf.
Edit ‘/etc/bind/named.conf’ file.
sudo gedit /etc/bind/named.conf
Make sure it contains the following lines.
include "/etc/bind/named.conf.options";
include "/etc/bind/named.conf.local";
include "/etc/bind/named.conf.default-zones";
31. sudo gedit /etc/bind/named.conf.local
Add the lines
zone "javed.local" {
type master;
file "/etc/bind/forward.javed";
allow-transfer { 192.168.1.102; };
also-notify { 192.168.1.102; };
};
32. zone "1.168.192.in-addr.arpa" {
type master;
file "/etc/bind/reverse.javed";
allow-transfer { 192.168.1.102; };
also-notify { 192.168.1.102; };
};
Here,
forward.javed – Forward zone file
reverse.javed– Reverse zone file
192.168.1.102 – Slave DNS server
33. Create forward zone
sudo gedit /etc/bind/forward.javed
Add the following lines:
$TTL 86400
@ IN SOA masterdns.javed.local. root.javed.local.(
2011071001 ;Serial
3600 ;Refresh
1800 ;Retry
604800 ;Expire
86400 ;Minimum TTL )
@ IN NS masterdns.javed.local.
@ IN NS secondarydns.javed.local.
@ IN A 192.168.1.101
@ IN A 192.168.1.102
@ IN A 192.168.1.103
masterdns IN A 192.168.1.101
secondarydns IN A 192.168.1.102
client IN A 192.168.1.103
34. sudo gedit /etc/bind/reverse.javed
Add follwing lines:
$TTL 86400
@ IN SOA masterdns.javed.local. root.javed.local. (
2011071002 ;Serial
3600 ;Refresh
1800 ;Retry
604800 ;Expire
86400 ;Minimum TTL )
@ IN NS masterdns.javed.local.
@ IN NS secondarydns.javed.local.
@ IN PTR javed.local.
masterdns IN A 192.168.1.101
secondarydns IN A 192.168.1.102
client IN A 192.168.1.103
101 IN PTR masterdns.javed.local.
102 IN PTR secondarydns.javed.local.
103 IN PTR client.javed.local.
35. Run the following commands one by one:
sudo chmod -R 755 /etc/bind
sudo chown -R bind:bind /etc/bind
36. Check DNS default configuration file:
sudo named-checkconf
/etc/bind/named.conf
sudo named-checkconf
/etc/bind/named.conf.local
If it returns nothing, your configuration is
valid.
37. sudo named-checkzone javed.local
/etc/bind/forward.javed
Sample output:
zone javed.local/IN: loaded serial 2011071001
OK
38. sudo named-checkzone javed.local
/etc/bind/reverse.javed
Sample Output:
zone javed.local/IN: loaded serial
2011071002
OK
Resatart bind9 service
sudo service bind9 restart
39. sudo gedit /etc/network/interfaces
Add the nameserver IP address:
auto eth0
iface eth0 inet static
address 192.168.1.101
netmask 255.255.255.0
network 192.168.1.0
broadcast 192.168.1.255
gateway 192.168.1.1
dns-nameservers 192.168.1.101
dns-search javed.local
Reboot your system.