Module 4: Planning, Optimizing, and
Troubleshooting DHCP
Overview
Planning a DHCP Strategy
Securing a DHCP Solution
Optimizing DHCP
Troubleshooting DHCP
Lesson: Planning a DHCP Strategy
Multimedia: Planning DHCP Server Placement in the Enterprise
Best Practices for Determining DHCP Server Placement
Choosing a DHCP Infrastructure
Defining Scope Reservations
Selecting DHCP Options
Selecting Option Classes
Guidelines for Planning a DHCP Strategy
Multimedia: Planning DHCP Server Placement in the Enterprise
The objective of this presentation is to plan the placement of DHCP servers in a Windows Server 2003 enterprise network
You will learn how to:
Explain the considerations for a single or multiple DHCP server plan
Determine when to use a single or multiple DHCP server solution to meet organizational requirements
Best Practices for Determining DHCP Server Placement
Best practice DescriptionPlace DHCP servers to minimize traffic across low-speed links
Place servers locally when you have a site that is across a slow link to minimize low-speed traffic
Place DHCP servers to optimize response times
Place DHCP servers to optimize response times for all clients on the LAN
Configure at least one backup server for fault tolerance
You can configure another server by using the 80/20 rule for scopes, configure a DHCP cluster, or use a standby server
Place DHCP server in a screened subnet
Place DHCP servers to provide services for a Web farm
Place DHCP servers close to population
Place DHCP servers on subnets with the highest client population or high lease renewals
Test server placement first in a lab
By testing server placement, you will validate your chosen plan
Choosing a DHCP Infrastructure
LAN 1LAN 1
DHCP server
LAN 2LAN 2
DHCP server
Remote LAN 3Remote LAN 3
DHCP server
Determining the type of DHCP infrastructure to be usedDetermining the type of DHCP infrastructure to be used
CentralizedDistributedMixed infrastructure
CentralizedDistributedMixed infrastructure
Defining Scope Reservations
Create a scope reservation when:Create a scope reservation when:
The device always requires the same address
Multiple DHCP servers service the reserved client
The client has a previously assigned IP address
More than one DHCP server can be reached by a reserved client
The device always requires the same address
Multiple DHCP servers service the reserved client
The client has a previously assigned IP address
More than one DHCP server can be reached by a reserved client
Selecting DHCP Options
DHCP option Description
Routers A preferred list of IP addresses for routers on the same subnet as the DHCP clients
DNS serversIP addresses for DNS name servers that DHCP clients use to resolve names
DNS domainDomain name that DHCP clients should use when resolving names
WINS node type A preferred NetBIOS name resolution method for the DHCP client to use
WINS server IP addresses of primary and secondary WINS servers for the DHCP client to use
Selecting Option Classes
Vendor-defined classes manage DHCP options identified by operating system vendor type
User-defined classes manage DHCP options with common configuration requirements
DHCP ServerDHCP Server
Client 2Client 2Windows 98 Client 1Windows 98 Client 1
Client 3Client 3
Vendor class configuration A
Vendor class configuration C
Vendor class configuration B
Guidelines for Planning a DHCP Strategy
Evaluate the network topologyEvaluate the network topology
Determine which DHCP infrastructure you will useDetermine which DHCP infrastructure you will use
Determine reservationsDetermine reservations
Define DHCP optionsDefine DHCP options
Determine integration issuesDetermine integration issues
Determine the fault tolerance approachDetermine the fault tolerance approach
Practice: Identifying DHCP Planning Issues
In this practice, you will determine a network configuration that meets the needs of the scenario
Lesson: Securing a DHCP Solution
Securing the DHCP Service
Preventing Unauthorized DHCP Servers
Securing DHCP in Screened Subnets
DHCP Administrators
DHCP Users
Active Directory
DHCP Server 1DHCP Server 1 DHCP Server 2DHCP Server 2
Securing the DHCP Service
Authorized ListAuthorized List
DHCP Server 1DHCP Server 1
DHCP Server 2DHCP Server 2
DHCP LogDHCP Log
Preventing Unauthorized DHCP Servers
Active DirectoryActive Directory
DHCP ServiceDHCP Service
Using DHCP servers in Windows 2000
Authorizing DHCP servers in Active Directory
Using DHCP servers in Windows 2000
Authorizing DHCP servers in Active Directory
DHCPINFORM DHCPINFORM
DHCP Server ObjectAuthorized ListDHCP Server ObjectAuthorized List
In authorized list(Startup)
In authorized list(Startup)
Not in authorized list(Shut down)
Not in authorized list(Shut down)
Authorized Windows Server 2003 DHCP Server
Authorized Windows Server 2003 DHCP Server
Unauthorized Windows Server 2003 DHCP Server
Unauthorized Windows Server 2003 DHCP Server
Securing DHCP in Screened Subnets
InternetInternet
External FirewallExternal Firewall
Internal FirewallInternal Firewall
DHCP ServerDHCP Server
Private NetworkPrivate Network
Screened SubnetScreened Subnet
DHCP ServerDHCP Server
Shared Resource ServerShared Resource Server
Web and Shared Resource ServerWeb and Shared Resource Server
Practice: Identifying Authorization Issues
In this practice, you will identify why clients are unable to access network resources.
Lesson: Optimizing DHCP
Improving the DHCP Server
Modifying Lease Duration
Improving the DHCP Server
Factors that impact DHCP server performance include: Factors that impact DHCP server performance include:
The speed of server disk drives.
The amount of RAM available on the DHCP server computer.
The speed of server disk drives.
The amount of RAM available on the DHCP server computer.
Modifying Lease Duration
Option When to use Result
Increase the lease duration
At least 20 percent of IP addresses in scope is availableConfigurations that rarely change on the network
Can reduce DHCP–related network traffic
Reduce the lease duration
Limited number of IP addresses availableClient configurations changeClients move often on your networkRemote access clients
Reduce the chance of running out of addresses to lease
Practice: Modifying Lease Duration to Improve DHCP Performance
In this practice, you will modify lease duration to improve DHCP performance
Lesson: Troubleshooting DHCP
Defining DHCP Problems
DHCP Troubleshooting Tools
Troubleshooting Common DHCP Issues
How to Troubleshoot DHCP Issues
Defining DHCP Problems
Is service operating
properly?
Are scopes configured
correctly?
Are leases available
for proper scopes?
Is the client properly connected
to the network?
Are you getting a
lease?
Where is the lease originating?
Are relay agents and routers
configured properly?
Are packets routing between
subnets?
How many clients are
affected?
Significant number ofclients affected
Only oneclient affected
Server-side issue
Client-side issue
Infrastructure issue
DHCP Troubleshooting Tools
Tool Purpose
Network Monitor For viewing packet-level information
DHCP Audit Log
Log DHCP events and critical errors
IPconfigFor generating DHCP traffic for testing purposes and reviewing current configuration
Troubleshooting Common DHCP Issues
Client-side problems
Server-side problems
Relay agent problems
DHCP database problems
How to Troubleshoot DHCP Issues
In this procedure, you will learn how to troubleshoot DHCP issues
Practice: Troubleshooting DHCP Issues
In this practice, you will determine DHCP troubleshooting steps
Lab A: Planning a DHCP Strategy
Exercise 1: Planning the DHCP Solution
Lab B: Troubleshooting DHCP Issues
Exercise 1: Optimizing DHCP Redundancy for Multiple Subnets
Exercise 2: Troubleshooting DHCP Problems