Dynamic Host Configuration Protocol

1
Chapter 5

• Dynamic Host Configuration Protocol

2
Learning Objectives

• Describe the dynamic host configuration protocol
  (DHCP)
• Describe the dynamic IP leasing process
• Configure a client to use DHCP
• Install the DHCP server service
• Configure scopes within the DHCP server service

continued
3
Learning Objectives

• Define and create scope options
• Authorize a DHCP server in Active Directory
• Configure DHCP for integration with DNS
• Manage, monitor, and troubleshoot DHCP

4
Overview of DHCP

• Provides an easy way for network administrators
  to provide IP addressing information for network
  clients
• Reduces the work associated with moving clients
  between subnets
• DHCP server service can be used to create a pool
  of IP addresses known as scopes that can be
  dynamically assigned to clients
• Options can include default gateway address, or a
  DNS and a WINS server address

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New Features of DHCP Server with Windows 2000

• Rogue DHCP server detection
• Integration with DNS
• Support for superscopes
• Support for multicast scopes
• Increased monitoring and management tools

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DHCP Lease Process

• Discover
• Offer

• Request
• Acknowledgment

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Step 1 DHCPDiscover
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Step 2 DHCPOffer
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Step 3 DHCPRequest
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Step 3 DHCPRequest
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Step 4 DHCPAcknowledgment
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DHCP Renewal Process
13
Configuring a Windows 2000 Server with the DHCP
Server Service

• Configure a static IP address, subnet mask, and
  default gateway on the server
• Install the DHCP server service
• Create scopes and, if needed, multicast scopes
  and superscopes
• Create and specify options on a server, scope,
  vendor-defined, user-defined, or reserved client
  basis
• Authorize the DHCP server in Active Directory

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Client Configuration for DHCP

• Any client that supports a standard
  implementation of DHCP can obtain an IP address
  from a Windows 2000 DHCP server
• To configure Windows clients, specify that they
  obtain an IP address automatically by accessing
  the Internet Protocols (TCP/IP) properties found
  under Local Area Connections properties

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Client Configuration for DHCP
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Installing the DHCP Server Service

• Minimum requirements
• Windows 2000 server machine configured with a
  static IP address, subnet mask, and, on networks
  with multiple subnets or networks, a default
  gateway
• Range of addresses that can be used to create
  scopes (ranges of IP addresses configured for
  lease to clients via DHCP)
• Active Directory installed and configured to
  allow DHCP servers to be authorized in AD

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Installing the DHCP Server Service

• Many ways to install DHCP
• One of the easiest ways is to access Network and
  Dial-up connections via the Start menu or
  right-click on My Network Places and select
  Properties

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Installing DHCP
19
Installing DHCP
20
Installing DHCP

• Common problem on networks attempting to
  implement DHCP routers do not pass broadcasts
• Solutions
• Configure a router to pass DHCP traffic
• Place second DHCP server on same segment as the
  client
• Use a DHCP relay agent to act as a proxy for a
  DHCP server

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Router Blocking DHCPDiscover Packets
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Configuring a DHCP Server per Physical Segment
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DHCP Relay Agents
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Configuring Scopes
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Items in theNew Scope Wizard

• Name and Description
• IP Address range
• Subnet mask
• Add Exclusions
• Lease duration
• Configure DHCP Options

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Configuring Scopes

• Multicast scopes
• Ranges of multicast addresses configured to be
  dynamically assigned to host via DHCP
• Superscopes
• Multiple scopes grouped together to allow
  centralized management
• Also allow for more than one range of IP
  addresses on a single physical subnet

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Reserving a Specific IP Address for a Specific
Client
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Scope Options

• Options that apply to all clients in one scope
  only
• Vendor-defined option classes
• User-defined option classes
• Reserved client options

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Main Options Used with DHCP
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DHCP and Active Directory

• Create a DHCP object within Active Directory to
  validate DHCP servers
• Requirements
• All DHCP servers must run Windows 2000
• First DHCP server in your network must be
  installed as either a domain controller or member
  server

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Integrating DHCP and DNS

• You can configure DHCP to create Dynamic DNS
  entries for clients that do not support DDNS
• Helps with support of legacy, non-DDNS aware
  clients
• Windows clients can register their own A records
  but they still rely on the DHCP server to create
  reverse lookup records

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Integrating DHCP and DNS
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Managing DHCP

• Create scopes, manage options, configure most
  DHCP settings with the DHCP snap-in
• Stop the DHCP service
• Compact the DHCP database with the jetpack
  command
• Manage DHCP clients with ipconfig/all,
  ipconfig/release, and ipconfig/renew
• Move DHCP database to a different DHCP server

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Monitoring DHCP

• Use DHCP snap-in for basic monitoring (server
  uptime, numbers of available addresses, number of
  leased addresses)
• Generate daily log of DHCP activity with DHCP
  audit log
• Perform detailed monitoring with System Monitor

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Monitoring DHCP with the DHCP Snap-in
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Monitoring DHCP with the Audit Log
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Monitoring DHCP with the Audit Log
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Monitoring DHCP with System Monitor
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Troubleshooting DHCP

• Misconfigured scopes or options
• Use ipconfig/all command to verify client
  settings and information
• Change options within the DHCP snap-in
• A stopped DHCP server service
• Use the net start dhcpserver command

continued
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Troubleshooting DHCP

• A scope that has run out of addresses
• Decrease length of lease for the scope
• Increase range of addresses in the scope
• Renumber entire scope with new, larger range of
  addresses
• Remove some clients from overcrowded network
  segment
• An improperly configured network
• Place a DHCP server on each subnet
• Implement DHCP relay agents on subnets without
  DHCP servers

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Chapter Summary

• Overview of DHCP
• Process used by clients to obtain dynamic IP
  addresses from a DHCP server
• Client configuration for DHCP
• Configuring scopes
• Scope options

continued
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Chapter Summary

• Installing and configuring a Windows 2000 server
  as a DHCP server
• Integrating a DHCP server with WINS and DNS
• Basic monitoring, troubleshooting, and management
  procedures for Windows 2000 DHCP servers