Durai presentation of dhcp
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Transcript of Durai presentation of dhcp
Dynamic Host Configuration Protocol(DHCP)
Objectives
• What is DHCP?• Describe the DHCP lease and renewal process• Install and authorize the DHCP service• Configure DHCP scopes• Create DHCP reservations for client computers• Configure DHCP options• Understand and describe the purpose of a
DHCP relay• Install and configure a DHCP relay
What is DHCP?
• It stands for Dynamic Host Configuration Protocol
• DHCP automatically assign the IP address to the
computer
• The ipconfig /all command will indicate whether the
configuration came from a DHCP server computer
How to assign IP address to a computer?
Leasing an IP Address
• An IP address is leased during the boot process
• Default lease period is 8 days
• Maximum lease period is 999 days
• Leasing an IP address is performed by DORA
process
DORA Process
• DORA process means
▫DHCP DISCOVER
▫DHCP OFFER
▫DHCP REQUEST
▫DHCP ACK
Simple network
Hello Mr. Server, I need to connect to the Internet, could you be kind to hook me up with an IP address?Ok dude, I got some in
my pool of address, I lend you it. Check it out?Your IP : 123.45.78.6
Thank you Mr. Server, I like your offer. I will use it.
You’re welcome, here is your configuration but it’s only for 3 days.
DHCP server discover
DHCP server offer
DHCP request
DHCP acknowledge
Router
Internet
DHCP Server
UDP Port 68
UDP Port 68
UDP Port 68
UDP Port 67
DHCP Clients
DHCP protocol is a mainly 4-step process:
DHCP ServerDHCP Clients
Broadcast
Unicast
Renewing an IP Address
•The IP address can either be permanent or timed•A permanent address is never reused for another
client•Timed leases expire after a certain amount of time•Windows clients attempt to renew their lease after
50% of the lease time has expired•A DHCP server may either honor or reject a renew
request
Renewing an IP Address (continued)
Installation of DHCP
• Install DHCP on Windows Server 2003
• Make sure your network connection is statically
configured
• Install the service using the Add/Remove Windows
Components utility
Installing DHCP service
Authorizing the DHCP Service
Authorizing the DHCP Service
• Unauthorized DHCP servers can hand out bad
information
• DHCP will not start unless authorized
• If Active Directory is used, authorization takes place in
Active Directory
• DHCP servers are automatically authorized under certain
conditions
Creating a Scope
• Create a scope to distribute IP addresses to client
computers
• Manually enter the IP configuration settings as
directed by the text
• Create a new scope using the configuration settings
provided
Configuring DHCP Scope
• Scope is a range of IP address
• Each scope is configured with:• Description
• Starting IP address
• Ending IP address
• Subnet mask
• Exclusions Range
• Lease duration
Configuring DHCP Scope
Types of Scope
• Super Scopes
• Multicast Scopes
Super scopes
• It is a collection of individual scope• Combine two scopes into a single logical unit using a
super scopes• First, create a second scope in addition to the scope
already created in a previous activity• Create a super scopes to encompass the two scopes• Use the DHCP snap-in for this activity
Super scopes
Multicast scopes
• It is used to deliver multicast address to a group of computers
• It is defined by using the following parameters• Starting IP address• Ending IP address• TTL• Exclusions• Lease duration
Creating DHCP Reservations• Reservations are used to hand out a specific IP
address to a particular client• Reservations are created based on MAC addresses
Configuring Relay agents
•DHCP packets cannot travel across a router•A relay agent is necessary in order to have a single
DHCP server handle all leases•Relay agents receive broadcast DHCP packets and
forward them as unicast packets to a DHCP server•The DHCP relay cannot be installed on the same
server as the DHCP service
Example with Relay Agent
Router
Internet
Relay agent
Router
67UDP
Broadcast
Source123.45.67.8Destination : 1.1.1.1Client IP : 123.45.68.7DHCPOFFER
123.45.67.8
BroadcastSource : 0.0.0.0Destination : 1.1.1.1DHCPDISCOVER
Unicast
Source : 123.45.67.8
Destination : 123.45.55.3
UnicastSource : 123.45.67.8
Destination : 123.45.55.3
DHCP Server
123.45.55.3
Unicast
Source : 123.45.67.8
Destination : 123.45.55.3Client IP: 123.45.68.7DHCPOFFER
Unicast
Source : 123.45.53
Destination : 123.45.68
Client IP : 123.45.68.7
New DHCP Client
68 UDP
23
Advantage
• It minimize the administrative burden• There is no chance to conflict IP address• It supports multiple scope like multicast scope and super
scope
Disadvantage • The machine name does not change when you get a new IP
address• When DHCP server is unavailable client unable to access
the network