MCTS Guide to Microsoft Windows
Server 2008 Network Infrastructure
Configuration
Chapter 4
Installing and Configuring the
Dynamic Host Configuration
Protocol
Objectives
• Discuss the basics of Dynamic Host Configuration
Protocol (DHCP)
• Describe the components and processes of DHCP
• Install DHCP in a Windows Server 2008 environment
• Configure the DHCP server
• Administer DHCP on clients and servers
• Troubleshoot DHCP
MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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Basics of DHCP
• DHCP
– Layer 4 protocol that uses User Datagram Protocol
(UDP) datagrams for communication
– Defined by Request for Comment (RFC) 2131
– Clients use UDP port 68 to send and receive DHCP
broadcast communication
– Servers use UDP port 67 to send and receive DHCP
broadcast communication
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Network Infrastructure Configuration
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MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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Exploring DHCP Components and
Processes
• DHCP lease
– Defines the amount of time, or the duration, that an IP
address is loaned to a DHCP client
• Lease duration
– Amount of time a client keeps an IP address before
releasing it
• DHCP scope
– A range of IP addresses and related configuration
information available by request from a DHCP client
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Network Infrastructure Configuration
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MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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Exploring DHCP Components and
Processes (continued)
• DHCP options
–
–
–
–
–
IP address
Subnet mask
Default gateway
Primary and secondary DNS servers
DHCP lease expiration
• DHCP reservations
– Allow you to assign a specific IP address to a DHCP
client without statically configuring the device with IP
information
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Network Infrastructure Configuration
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MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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Network Infrastructure Configuration
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DHCP Communication Processes
• DHCP message types
– DHCPDiscover, DHCPOffer
– DHCPRequest, DHCPAck
– DHCPNack, DHCPDecline
• Initial lease request
– Clients make these requests if they do not have a
current lease on a scope
• Lease renewals
– Intervals: Renewal time value and Binding time value
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Network Infrastructure Configuration
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MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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DHCP Communication Processes
(continued)
• Changing subnets
– When a client moves to a new subnet, it cannot use
its current lease because the IP information does
match the new network configuration
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Network Infrastructure Configuration
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MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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Using DHCPv6
• IPv6 clients
– Use DHCP to receive IP address and configuration
information from an IPv6 router on their network
• Implementing DHCPv6 requires
– Configuring your router to forward all
autoconfiguration requests to an available DHCPv6
server
– Disabling stateless mode on your Windows Server
2008 DHCP servers
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Network Infrastructure Configuration
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Installing DHCP in a Windows
Server 2008 Environment
• DHCP Server role
–
–
–
–
Requires minimal server resources
Starts the DHCP Server service
Installs the files needed for the DHCP database
Initializes the DHCP console on the local system
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Network Infrastructure Configuration
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Installing DHCP in a Windows Server
2008 Environment (continued)
• Activity 4-1: Installing the DHCP Server Role
• Time Required: 15 minutes
• Objective: Install the DHCP server role
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Network Infrastructure Configuration
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Installing DHCP in a Windows Server
2008 Environment (continued)
• DHCP database
– Based on the Joint Engine Technology (JET) storage
engine
– Database size is based on the number of client
requests it receives
• DHCP Server service
– Installed with the DHCP Server role
• DHCP Server console
– The GUI tool for managing DHCP on Windows Server
2008
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Network Infrastructure Configuration
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Installing DHCP in a Windows Server
2008 Environment (continued)
• Activity 4-2: Reviewing the DHCP Server Console
• Time Required: 5 minutes
• Objective: Explore the DHCP Server console
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Network Infrastructure Configuration
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Authorizing DHCP
• In Active Directory domains
– DHCP servers must be authorized before they can
begin supplying IP addresses
• In Windows Server 2008
– You are prompted for credentials during installation if
your server is a member of a domain
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Network Infrastructure Configuration
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Configuring the DHCP Server
• After installing the DHCP role
– You need to configure DHCP for its initial use
• DHCP
– Requires at least one DHCP scope to issue IP
addresses for network clients
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Network Infrastructure Configuration
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Configuring the DHCP Server
(continued)
• Activity 4-3: Creating a Scope for the
192.168.100.0 Subnet
• Time Required: 10 minutes
• Objective: Create scopes in the DHCP console
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Network Infrastructure Configuration
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Configuring the DHCP Server
(continued)
• Activity 4-4: Creating a Scope for an IPv6 Subnet
• Time Required: 10 minutes
• Objective: Create an IPv6 scope in the DHCP
console
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Network Infrastructure Configuration
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Configuring the DHCP Server
(continued)
• Activity 4-5: Activating an IPv4 DHCP Scope
• Time Required: 5 minutes
• Objective: Activate a DHCP scope
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Network Infrastructure Configuration
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Configuring the DHCP Server
(continued)
• Activity 4-6: Expanding an IPv4 Address Pool
• Time Required: 5 minutes
• Objective: Modify an IPv4 address pool
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Network Infrastructure Configuration
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Configuring Exclusions
• Exclusions are created so that:
– Static IP addresses for devices such as routers,
printers, or other network devices are not assigned
• Common practice
– Create exclusionary ranges at the beginning and end
of a scope range
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Network Infrastructure Configuration
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Configuring Exclusions (continued)
• Activity 4-7: Adding IPv4 Exclusion
• Time Required: 10 minutes
• Objective: Create IPv4 exclusionary ranges
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Network Infrastructure Configuration
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Configuring Options
• Options
– Allow you to quickly and easily provide DHCP clients
with updated configuration information
• If you are using the default lease duration of eight
days
– Could take up to four days before clients receive the
new DHCP options you deploy
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Network Infrastructure Configuration
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Configuring Options (continued)
• Activity 4-8: Modifying the Server Options
• Time Required: 10 minutes
• Objective: Modify the DHCP server options
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Network Infrastructure Configuration
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Configuring Options (continued)
• Activity 4-9: Modifying the Scope Options
• Time Required: 10 minutes
• Objective: Modify the DHCP scope options
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Network Infrastructure Configuration
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Creating Reservations
• Reservations
– Used in DHCP to give a DHCP client a static IP
address without manually configuring the address on
the client
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Network Infrastructure Configuration
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Creating Reservations (continued)
• Activity 4-10: Adding a Reservation for
192.168.100.225
• Time Required: 5 minutes
• Objective: Add a reservation for a new network
printer
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Network Infrastructure Configuration
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Using netsh
• Syntax for creating a DHCP reservation
netsh Dhcp Server 192.168.100.10 Scope
192.168.150.0 add reservedip
192.168.150.20 03043c40fb6a MSN-SRV-150
• Syntax for creating a DHCP exclusionary range
netsh Dhcp Server 192.168.100.10 Scope
192.168.150.0 add excluderange
192.168.150.1 192.168.150.10
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Network Infrastructure Configuration
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DHCP Client Configuration
• DHCP Client service
– Responsible for the DHCP configuration process on a
client machine
• Fault tolerance and DHCP
– Microsoft recommends using an 80/20 rule for splitting
scopes between two servers for fault tolerance
– 80/20 rule
• 80 percent of a scope’s total IP range is hosted on your
primary DHCP server, while the remaining 20 percent is
hosted on your secondary DHCP server
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Network Infrastructure Configuration
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MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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DHCP Administration
• Monitoring reliability and performance
– Monitoring allows you to determine the current state of
DHCP
– Reliability and Performance Monitor
• Used to create a real-time picture of what is happening
on the local or remote server
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Network Infrastructure Configuration
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Monitoring Reliability and
Performance
• Activity 4-11: Adding Counters to Performance
Monitor
• Time Required: 10 minutes
• Objective: Configure Performance Monitor by
adding DHCP Server counters
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Network Infrastructure Configuration
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Monitoring Reliability and
Performance (continued)
• DHCP console statistics
– Server statistics: broader and provide a more
comprehensive picture of the status of your DHCP
server
– Scope statistics: display information about each scope
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Network Infrastructure Configuration
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Monitoring Reliability and
Performance (continued)
• Activity 4-12: Viewing Statistics
• Time Required: 5 minutes
• Objective: View server and scope statistics
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Network Infrastructure Configuration
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Monitoring Reliability and
Performance (continued)
• DHCP audit log
– Lists detailed information about events occurring on
a specific day, including
• Event ID, Date and time
• Event description, IP address
• Host name, MAC address
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Network Infrastructure Configuration
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Monitoring Reliability and
Performance (continued)
• Activity 4-13: Viewing Audit Logs
• Time Required: 10 minutes
• Objective: View audit logs
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Network Infrastructure Configuration
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Backup and Recovery
• Automatic backup
– Windows Server 2008 performs an automated
backup of the DHCP database every 60 minutes
• Manual backup
– Stored in the
%systemroot%\systemroot\dhcp\backup folder
• Restoring the DHCP database from a backup
– You can restore a DHCP database from an offline
backup when you are building a new DHCP server
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Network Infrastructure Configuration
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Backup and Recovery (continued)
• Activity 4-14: Performing a Manual Backup
• Time Required: 10 minutes
• Objective: Back up the DHCP database
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Network Infrastructure Configuration
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Backup and Recovery (continued)
• Activity 4-15: Restoring a DHCP Database
• Time Required: 10 minutes
• Objective: Restoring the DHCP database
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Network Infrastructure Configuration
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Troubleshooting DHCP
• Reconciling the database
– Validates the DHCP database by comparing it with
the Registry values of the operating system to verify
that the database contains the most current data
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Network Infrastructure Configuration
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Troubleshooting DHCP (continued)
• Activity 4-16: Reconciling the DHCP Database
• Time Required: 10 minutes
• Objective: Reconcile individual and all scopes in
the DHCP console
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Network Infrastructure Configuration
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Verifying DHCP Services
• To determine the running services on a system
– Enter the net start command at a command prompt
• To stop a running service
net stop “DHCP Server” or “DHCP Client”
net start “DHCP Server” or “DHCP Client”
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Network Infrastructure Configuration
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Troubleshooting DHCP Clients:
IPconfig
• ipconfig
– Can be used to renew the current IP address and
configuration information and to release the current
IP address
• Entering the ipconfig /release command
– Issues the DHCPRelease message to the server
currently holding the IP address lease for a client
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Network Infrastructure Configuration
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MCTS Guide to Microsoft Windows Server 2008
Network Infrastructure Configuration
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Network Infrastructure Configuration
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Summary
• Information provided by a DHCP server includes:
– Leases, scopes, and options
• For DHCP to function properly in a routed network:
– A DHCP relay agent or an RFC 1542–compliant
router needs to be in place to pass along DHCP
messages
• DHCP
– Uses a standard set of messages for communicating
between DHCP clients and DHCP servers
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Network Infrastructure Configuration
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Summary (continued)
• Common communication processes
– Initial lease requests, lease renewals, and changing
subnet renewals
• All data in DHCP is stored in the DHCP database
• Only DHCP servers in an Active Directory domain
need to be authorized
• After DHCP is installed
– You must configure scopes for DHCP clients to
receive addresses
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Network Infrastructure Configuration
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Summary (continued)
• DHCP console or netsh
– Can be used to perform all configuration tasks
• DHCP
– Uses exclusions to prevent making the IP addresses
of statically assigned devices available in an IP
scope range
• To monitor DHCP
– Use Performance Monitor, DHCP statistics, and the
DHCP audit log
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Network Infrastructure Configuration
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Installing and Configuring the Dynamic Host Configuration Protocol