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Overview of the DHCP Server Role

Benefits of Using DHCP New DHCP Features in Windows Server 2008/R2

How DHCP Allocates IP Addresses

How DHCP Lease Generation Works

How DHCP Lease Renewal Works

DHCP Server Authorization

Demonstration: How to add the DHCP Server Role

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Benefits of Using DHCPDHCP reduces the complexity and amount of administrative work by using

automatic TCP/IP configuration

Manual TCP/IP Configuration

IP addresses are enteredmanually

IP address could be enteredincorrectly

Communication and networkissues can result

Frequent computer movesincrease administrative effort

Automatic TCP/IP Configuration

IP addresses are suppliedautomatically

Correct configurationinformation is ensured

Client configuration is updatedautomatically

A common source of networkproblems is eliminated

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New DHCP Features in Windows Se2008

New DHCP features include:

Windows Server 2008 Support for DHCPv6

Support for advanced network securityconfiguration using NAP

DHCP on Server Core

These new features were added with Windows Server 2008

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How DHCP Allocates IP Addresses

DHCP Server

DHCPDatabase

IP Address1: Leased to DHCP Client1

IP Address2: Leased to DHCP Client2

IP Address3: Available to be leased

DHCP Client2:

IP configuration

from DHCP server

Non-DHCP Client:

Static IP

configuration

DHCP Client1:

IP configuration

from DHCP server

Lease Renewal

Lease Generation

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How DHCP Lease Generation Work

DHCP client broadcasts a DHCPDISCOVER packet1

DHCP servers broadcast a DHCPOFFER packet2

DHCP client broadcasts a DHCPREQUEST packet3

DHCP Server1 broadcasts a DHCPACK packet4

DHCP

Client

DHCP

Server1

DHCP

Server2

DHCP client broadcasts a DHCPDISCOVER packet1

DHCP servers broadcast a DHCPOFFER packet2

DHCP client broadcasts a DHCPREQUEST packet3

DHCP Server1 broadcasts a DHCPACK packet4

DHCP

Client

DHCP

Server1

DHCP

Server2

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How DHCP Lease Renewal Works

DHCP Client sends a DHCPREQUEST packet1

DHCP Server1 sends a DHCPACK packet2

If the client fails to renew its lease, after 50% of the lease duration hasexpired, then the DHCP lease renewal process will begin again after 87.5% ofthe lease duration has expired

If the client fails to renew it s lease, after 87.5% of the lease has expired, then

the DHCP lease generation process starts over again with a DHCP clientbroadcasting a DHCPDISCOVER

DHCP ClientDHCP

Server1

DHCP

Server2

50% of leaseduration hasexpired

87.5% of leaseduration hasexpired


DHCP ClientDHCP

Server1

DHCP

Server2

DHCP client sends a DHCPREQUEST packet1

DHCP Server1 sends a DHCPACK packet2


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Configuring DHCP Scopes

What Are DHCP Scopes? What Is a DHCP Reservation?

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What Are DHCP Scopes?

A scopeis a range of IP addresses that are available to be leased

Scope Properties

Scope name

Exclusion range

Lease duration

Network IPaddress range

Network ID

Subnet mask

LAN A LAN B

DHCP Server

Scope BScope A

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What Is a DHCP Reservation?A reservationis a specific IP address, within a scope, that is reserved permanentlyfor lease to a specific DHCP client

Subnet A Subnet B

Workstation 1

DHCP ServerWorkstation 2

File and PrintServer

IP Address1: Leased to Workstation 1

IP Address2: Leased to Workstation 2

IP Address3: Reserved for File and Print Server

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What Are DHCP Options?

WINS Servers

Common scope options are:

DHCP optionsare values for common configuration data that applies to the

server, scopes, reservations, and

class options

DNS Servers

DNS Name

WINS Servers

Default Gateway

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How DHCP Options Are Applied

DHCP options can be applied at various levels:

Server

Scope

Reserved client

Class

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Overview of DHCP ManagementScenarios

Scenarios for managing DHCP:

The DHCP service needs to be managed to respond to network changes

Managing DHCP database growth

Protecting the DHCP database

Ensuring DHCP database consistency

Adding clients

Adding new network service servers

Adding new subnets

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DHCP Server Configuration Options

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What Is a DHCP Database?

Windows Server 2003 stores the DHCP database in the%Systemroot%\System32\Dhcp folder

The DHCP database files include:

Dhcp.mdb

Dhcp.tmp

J50.log and J50*.log

Res*.log

J50.chk

The DHCP databaseis a dynamic database that contains configuration information

The DHCP database contains DHCP configuration data such as:

Scopes

Address leases

Reservations

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Monitoring and Troubleshooting DH

Common DHCP Issues What Are DHCP Statistics?

What Is a DHCP Audit Log File?

Monitoring DHCP Server Performance

Demonstration: How to Monitor DHCP

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Common DHCP Issues

Address conflicts

Failure to obtain a DHCP address

Address obtained from incorrect scope

DHCP database suffered data corruption or loss

DHCP server has exhausted its IP address pool

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What Are DHCP Statistics?DHCP statisticsare collected at either the server level or scope level

DHCP Server

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What Is a DHCP Audit Log File?A DHCP audit logis a log of service-related events

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Monitoring DHCP Server Performan

Create a DHCP performance baseline

Check the standard counters forserver performance

Review DHCP server counters for significantchanges in DHCP traffic

Performance

counters

What to look for after a

baseline is established

Packetsreceived/second

Monitor for sudden increases or decreases, whiccould reflect network problems

Requests/secondMonitor for sudden increases or decreases, whiccould reflect network problems

Active queue

length

Monitor for sudden and gradual increases, whichcould reflect increased load or decreased servercapacity

Duplicatesdropped/second

Monitor for any activity that could indicate thatmore than one request is being transmitted onbehalf of clients

02_DHCP

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