DHCP (Dynamic Configuration Host protocol)

IPs: (Internet Protocols) 
There are two versions in IP1. Version 4.0
2. Version 6.0

IPs are of two types 20 Static IPs
21 Dynamic IPs

Static IP: 

Static IPs are IPs what an admin assigns to the computer manually. Which are not changeable.

Dynamic IPs:

Are the IPs, which are assigned by DHCP server, which are dynamic. i.e. not constant, changeable.

DHCP: 

Useful for extremely larger networks where we want to centralize the I.P. management to reduce human errors.
Case2: Useful for smaller networks where there are no administrators or administrator may not be comfortable with assigning IPs.

ISP – Internet Service Provider
Usually ISPs implement DHCP servers

DHCP is a server which assigns IPs to the clients requested automatically from a range of IPs.

IP leasing process: 
1. DHCP discover: 

The client machine when turned ON broad casts the network id, broad castes id, MAC address on Network for discovering DHCP server.

2. Offer: 

The DHCP server listening to the request made by the client offers a pool of IP addresses to the client machine.

3. Selection:

The client machine on receiving the pool of IP address selects an IP and requests the DHCP server to offer that IP

4. Acknowledgement: 

The DHCP sends a conformation about the allotment of the IP assigned to the client as an acknowledgement.

5. IP lease:

If the client machine is not restarted for 8 days, exactly after 4days the client machine requests the DHCP server to extend the IP lease duration, on listening to this the DHCP server adds 8 more days for existing 4 days =12 days

If the client machine is restarted again the DHCP lease process takes place and again the client gets an IP for 8 days.

DHCP requirements:

DC or member serverStatic IP
AD
DNS (if it is win 2003)

Installing DHCP server (insert 2003 server CD) :

On DC
Start - setting – control panel – add\remove programs – add \rem windows components - Select n/w services – click on details
Select DHCP server – ok – next

Authorization:

When we have multiple DHCP servers we can designate one of the DHCP servers as an authorized DHCP server.

Authorizing DHCP server: 

On DC
Start >p>admin tools
DHCP right click on the server
Click authorize
Refresh

Scope:

Scope is a range of IP addresses from which the DHCP server assigns IPs to the clients.

Creating a Scope: 

Open DHCP Server
Right click on server
New scope- scope name
Specify the range next
Specify if we want any exclusion
Lease duration
Next – DHCP options
Router – next – specify the domain name
Server name – client on resolve – add – next – WINS server – next - yes I want – next – finish

Configuring a client machine to obtain IP from DHCP server 

By default all the clients configured as obtain IP automatically
On client machine
Right click on my n/w places
Properties – LAN properties
TCP/IP double click
Ensure that “obtain an IP address automatically” is selected.

Releasing an existing IP: (give up an IP)

Start >run>cmd>ipconfig /release

Obtaining a new IP 
Start >run>cmd>ipconfig /renew

Super Scopes: 
Group of scopes is called as super scope.

Note: 

When we have multiple scopes only one scope can be active in order to enable all the scopes we have to merge all the scopes with super scope.

Creating super scope:
Requires multiple scopes
Create 2 scopes.
Right click on server
Say new super scope
Specify the super scope name
Select 2 scopes by holding ctrl key
Next – finish

Address Pool: gives the range of IP addresses we have specified
Address leases: specifies the client (names) and the IP addresses assigned
Reservations: useful when we want to dedicate a particular IP to a particular system.
Ex: managerial systems, important clients.



To check the MAC address 

Start-run-cmd>getmac

To check the MAC address of remote system
Start-run-cmd>getmac /s \\systemname

Implementing reservation: 

Open DHCP
Right click on reservations
New – reservation – give name - mention reservation name - MAC address of the remote machine – mention the IP address to be reserved
Close

Move on to client machine:

Start - run – cmd – ipconfig /release – ipconfig - /renew

Scope options: 

Using scope options we can specify the other servers addresses available in the network. So that the DHCP server maintains information about all other servers and provides it to the client machines along with the I.P. addresses.
For NT – 66servers addresses - for 2000-03 - 77

Server options: 

Useful when we have multiple scopes and provide information to all the scopes. Where as scope options are limited only to that scope.

Backing up DHCP: 
Open DHCP - right click on DHCP – select backup
Select location where we want to save – ok

Restoring DHCP server: 

Uninstall DHCP server
Install DHCP server
Open DHCP
Right click on it
Click on restore – specify the backed up path
We should notice our previous scopes.