1. DNS SERVER (Domain Name System)
DNS Concept
The DNS stands for Domain Name System. It works on 53 no. port. DNS is used to
resolve name to IP address of the host computer. DNS is also called Database which
stores host records. DNS is available in Windows Server 2000 and Windows Server 2003
operating system.
DNS is introduced in 2000 with Window Server 2000. Domain
Name is Hierarchal Structure.
Difference between NetBIOS Name and Domain Name
NetBIOS Name Domain Name
(1) It is 15 characters long. (1) It is 255 bytes long.
(2)It has flat structure means no sub (2) It is Hierarchal structure ,
NetBIOS Names. means roots, top level
Domains, second level
Domains and host
Computers.
(3)The primary method to resolve (3) The primary method to
NetBIOS over TCP/IP is WINS resolve name to IP address
Server in previous Win 2000. of the host computer is
DNS Server.
FQDN
www.yahoo.com .
Host Second Top Root
Computer Level Level
DNS Lookup Types: -
By default, DNS has two Lookup types
(i) Forward Lookup
(ii) Reverse Lookup
(i) Forward Lookup
The forward lookup is used to store zones, which are responsible for resolve name to
IP address of the Host computer. Under forward lookup type, we can create or store
Primary Zone, Secondary Zone, and Stub Zone.

2. (ii) Reverse Lookup
Reverse lookup is used to resolve IP address to name of the Host computer. This is
very rarely configure because mostly it is used for in troubleshooting purpose in the
NS Lookup.
Zone Types: -
DNS has three types of zones
(i) Primary Zone
(ii) Secondary Zone
(iii) Stub Zone
(i) Primary Zone
In DNS server, we have to create zones under forward lookup type to configure the
DNS server. Zone is also called Database, which stores Host records of the computer
(NetBIOS Name and IP address). Primary Zone has read and write access. We can
update data directly in this zone. This zone is available on first DNS server in the
network or we can say this Zone is available on Primary DNS server. It keeps original
data. This zone is also responsible for store Host records and resolve name to IP
address.
(ii) Secondary Zone
This zone is also available under the forward lookup type. We can configure this kind
of zone on secondary DNS server. It has read only access. You can not update data
directly on this zone. It has copy of Primary zone. We can configure secondary DNS
server with Secondary zone for the purpose of fault tolerance.
For e.g:- we can configure secondary DNS server with secondary zone with Additional
Domain Controller. Zone and Data is replicated from Primary DNS server to secondary
DNS server by using zone transfer option process. It keeps copy of Primary original data
or Primary zone.
(iii) Stub Zone
Stub zone does not provide any kind of service like Primary and Secondary zone. It
stores special kind of records like NS record (Name of Server) and SOA record (Start of
Authority).
Records types:-
(i) A Record [Host Record]
(ii) Alias Record ( c Name )
(iii) MX Record [Exchange server, Mail server, @domain name (e-mails) ]
(iv) NS Record - Name of Server
(v) SOA Record - Start of Authority
(vi) SRV Record - Service Location Record

3. Installation of DNS Server
(1) log on as a Administrator
(2) go to control panel -> Add/Remove Programs -> Add/Remove Components ->
Network Services -> then click on Detail button -> then check the check box of
DNS.
(3) Click ok.
(4) Click next to install the DNS server.
You can access DNS server from Administrator Tools.
DNS Suffix is used to resolve Name to IP Address of the Host Computer. It is also used
to register Host Records of the client computers in DNS server dynamically.
In real means DNS Suffix is the name of the Primary Zone configured in the
Primary DNS server.
Steps to assign DNS Suffix
(1) Log on as Administrator.
(2) Configure TCP/IP. IP Address, Subnet Mask and Preferred DNS IP Address.
(3) Now right click on My Computer icon then Properties -> Computer Name Tab ->
Change button -> More button.
(4) In the Primary DNS Suffix text box. Type the name of the DNS Suffix.
(5) Click ok and restart your computer.
To make member of DNS
On workgroup computer, Fill Suffix name of Domain and Restart PC or type command
on Command Prompt C:>ipconfig/registerdns.
Dynamic Updates
Dynamic Updates are updates which are registered in DNS server dynamically. Here
Dynamic updates are Host records of the client computer (Name & IP Address). These
updates are registered in DNS server dynamically with the help of DNS Suffix.
When your DNS server accepting Dynamic Updates then your DNS server is
called DDNS (Dynamic DNS).
We can also set Dynamic Update acceptance behavior of the DNS server, in
which we have three options:-
(i) Secure only
In this option only active directory clients can register their Host Record in DNS
server.
(ii) Secure and Non-Secure only

4. In this option active directory clients and workgroup clients, Both can able to register
their Host record in DNS server.
(iii) Do not Allow
In this option no one can register their Host record in DNS server.
You can also change these options by zone properties.
DNS with Active Directory
DNS server plays a very important role in Domain Environment. We can also say Active
Directory is tightly integrated with DNS server or DNS is a backbone of Active
Directory. Active Directory can not work without DNS server.
When we install Active Directory with DNS server then A.D registers its Domain
Name in DNS server, when we join clients in Domain Environment then we have to
provide IP Address of the DNS server to our client computers. First request goes to DNS
server. DNS server locates the Domain Controller and the request shifted to Active
Directory. So in this way client computers join Domain environment.
Protocol/Port No.
=> Protocol used in Active Directory is LDAP (Light Weight Directory Access Protocol)
and the Port no. is 389.
DNS with WAN
Top level Domain
.Com
.Edu
.Net
.Co.in
.Org
.Ca
.Uk
.Mil
Root Server
We have 13 Root servers. This is available on the top of the Hierarchal Structure in
Domain Name System. Microsoft provides the name & IP Address of Root Servers in the
DNS server.
When a DNS server receives a query from a client, First of all, it will try
to resolve the query. if it has no answer then DNS server go to Root server on the Internet
by using Root Hints (List of Name & IP Address of Root Servers).

5. Query Type
(1) Recursive Query
(2) Iterative Query
(3) Referral Query
(1) Recursive Query
Client to DNS
(2) Iterative Query
DNS performs query on behalf of its clients.
(3) Referral Query
Appro: answer provided by Root and Com.
When client receives proper answer from DNS Server then one Recursive Query is
completed. The whole process which is performed on behalf of client is called Recursion.
By default, Recursion option is enabled in DNS server.
Types of DNS Server
(1) Primary DNS Server
(2) Secondary DNS Server
(3) Cache Only DNS Server
Primary DNS Server
This is a first DNS Server in the network. It contains original data. It has Primary Zone
under forward lookup.
Secondary DNS Server
This is a second DNS server in the network also act as a Backup Server. We can also say
Secondary DNS server is used to provide fault tolerance in the network. It has Secondary
Zone under the Forward Lookup Zone and Data is replicated from Primary to Secondary
DNS server by Zone transfer process. It has read only access. Secondary DNS server
queried to its master server for new updates after every 15 minutes.
Cache Only DNS server
This is the type of DNS server. It has no Zone. But it has Cache, Root Hints and one
another thing Forwarders.
There is no additional configuration required in Cache Only server. We
will just install DNS role in the computer.

6. Between two offices
(Branch office and Head office)
But in this case we have to configure Forwarders. In which we will provide Domain
Name and IP address of DNS server, Which is responsible for this Domain Name Zone.
C:>ipconfig/flushdns
Clear your cache and read the correct information from your DNS.

7. DHCP Concept
DHCP stands for Dynamic Host Configuration Protocol. It is used to provide or assign
IP v4 addresses to the configure clients within the same network or between two subnets.
In window server 2003, DHCP server is not installed by default. Difference
between static IP address and dynamic address.
Static IP address Automatic IP address (DHCP)
(1) More time consuming practice. (1) Very less time required.
(2) We have to maintain a list. (2) No need, list is maintained by
DHCP.
(3) If wrong information is delivered then (3) No chance to deliver wrong
may be communication problem occurred. Information.
(4) If same information delivered again then (4) No chance.
may be IP address conflict with each other.
(5) More overhead on administrator. (5) Less overhead on administrator.
(6) If computer is shuffling from network then (6) In case shuffling, no problem of
may be communication problem occur. Communication.
DHCP Server working
DHCP
Static IP 10.0.0.10 Scope
255.0.0.0
10.0.0.10
Scope Name
IP address
Start IP address
End IP address
Subnet mask
Exclude the IP from distribution
10.0.0.10
10.0.0.15
Router IP address
Parent Domain Name (DNS Suffix)
DNS IP address
WINS IP address
Lease

8. DORA Process
DHCP Server is used to provide IP address. We can configure DHCP Server by making a
scope. In which we can provide lots of information, which is assigned to the client
computer.
A DHCP Server has always Static address. When we configure our client
computer obtain IP address automatically then a DORA process communication is
performed between DHCP Server and DHCP Client.
(1) DHCP Discover
When client computer is DHCP enabled then it will start finding DHCP Server by
using broadcast communication with the broadcast message packet. The
information is attached by client is his NetBios Name, mac address, s port, d port
etc. This message packet is also called Discover Packet.
(2) DHCP Offer
When a client computer sends broadcast message in the network then DHCP
server receives the DHCP Discover Packet and offer IP related information to the
requesting client.
(3) DHCP Request
When DHCP Server offer IP address related information to the requesting client
then requesting client request s the DHCP Server for IP address or IP selection
request to DHCP Server.
(4) DHCP Acknowledgement
When DHCP Server receive the request from requesting client for IP address
related information then he sends acknowledgement to the requesting client and
maintain his record in its database in which IP address, NetBios Name, Lease
expire date & time and Mac address which is also called Unique Id.
We can see or view assigned information on client computer by using command prompt
with the help of following command: -
C:>ipconfig/all

9. Scope
Scope has IP related information, which is used to assign to the DHCP client computers
dynamically. The information is IP address, exclude the IP from distribution, router IP
address, parent domain name (DNS suffix), DNS IP address, WINS IP & Lease etc.
Creating Scope
In one subnet we can create single scope, but in case of multiple subnet we can create two
scopes with different subnet. To create the scope, open DHCP Server.
Right click on Server Local then New scope.
A new scope wizard appears on screen.
Scope Sub containers
(i) Address Pool
In this sub container, it will contain Start range IP address & End range IP
address as specified by the administrator. It will also contain Excluded IP
address. You can exclude more IP address or IP address range by right click
on this container.
(ii) Address Leases
In this sub container, it will show the list of assigned IP addresses & NetBios
Name of its clients, Lease expiration date & time, Unique Id which is mac
address of client computer.
(iii) Reservation
Reservation is used to ensure that a DHCP client is always assigned the same
IP address. We can bound IP address with the client computer by using client
computer’s mac address. By using right click on this container, we can reserve
IP address for our client computer.
Super Scope
Super scope is a scope, which is used to handle multisubnet scopes. We can configure
this Super scope when our DHCP Server is configured to provide IP address between two
subnets or we can say when we want to centralized our IP address assignment method
between two subnets.
Lease
Lease is a time duration offered by DHCP Server to the requesting client that how long a
client computer can use IP address. By default lease duration is 8 days. A client computer
can renew its lease after 50% of its lease duration. At the time of renewable request if
DHCP Server is not available then the second request sends by the DHCP client at 87.5%
of leased duration. We can renew leased duration manually by using following
commands: -
To renew the lease duration first of all we have to release the IP address then send the
renew request. To release the IP address the command is: -

10. C:> ipconfig/release
(To remove configure or lease from DHCP database)
When you execute this command a release message will send to the DHCP Server to
release the information from his database. In this process client computer will use 0.0.0.0
as a source address. To renew the leased duration the command is
C:>ipconfig/renew
A New lease duration is assigned to the client computer by DHCP Server.
Installation of DHCP Server
Go to control panel ->
Then Add/Remove programs ->
Add/Remove windows components then network services ->
Then detail -> Then DHCP
Check this check box, click ok.
Click Next to install the DHCP.
You can access it from Administrator Tools.
DHCP Domain Environment
If you are going to install DHCP server in Domain environment then we have to
authorize the DHCP Server from Active Directory means no other unauthorized DHCP
Server will assign IP address to the client computer.
There are two methods to authorized the DHCP Server in Domain Environment
(1) open DHCP Server console. Right click on server local -> then click Authorize.
It will show you green sign.
(2) Open DHCP console.
In the left pane, Right click on DHCP icon in the top of the list then manage
authorize server.
A new dialog box appears on screen. Click on authorized button.
Type the IP address of DHCP Server. click ok.
It will show you full computer name with IP address of that computer. Click ok.
Again select the IP address from the list to whom you want to authorized and
click ok.
DHCP in Workgroup Environment
In case of workgroup environment, DHCP Server computer must be a fresh workgroup
computer means it will not be a member of a Domain Controller otherwise it will demand
you authorized from Active Directory. But in workgroup environment every computer is
independent computer and act as server, so there is no need to authorized from Active
Directory.