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
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.
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.
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