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Configuring DHCP
DHCP Configuration Task List
IPC-68
Cisco IOS IP Configuration Guide
DHCP Configuration Task List
The DHCP Server database is organized as a tree. The root of the tree is the address pool for natural
networks, branches are subnetwork address pools, and leaves are manual bindings to clients.
Subnetworks inherit network parameters and clients inherit subnetwork parameters. Therefore, common
parameters, for example the domain name, should be configured at the highest (network or subnetwork)
level of the tree.
Note Inherited parameters can be overridden. For example, if a parameter is defined in both the natural
network and a subnetwork, the definition of the subnetwork is used.
Address leases are not inherited. If a lease is not specified for an IP address, by default, the DHCP
Server assigns a one-day lease for the address.
To configure the Cisco IOS DHCP Server feature, perform the tasks described in the following sections.
First configure a database agent or disable conflict logging, then specify IP addresses that the DHCP
Server should not assign (excluded addresses) and should assign (a pool of available IP addresses) to
requesting clients. The tasks in the first three sections are required. The tasks in the remaining sections
are optional.
• Enabling the Cisco IOS DHCP Server and Relay Agent Features (Optional)
• Configuring a DHCP Database Agent or Disabling DHCP Conflict Logging (Required)
• Excluding IP Addresses (Required)
• Configuring a DHCP Address Pool (Required)
• Configuring Manual Bindings (Optional)
• Configuring a DHCP Server Boot File (Optional)
• Configuring the Number of Ping Packets (Optional)
• Configuring the Timeout Value for Ping Packets (Optional)
• Enabling the Cisco IOS DHCP Client on Ethernet Interfaces (Optional)
• Configuring DHCP Server Options Import and Autoconfiguration (Optional)
• Configuring the Relay Agent Information Option in BOOTREPLY Messages (Optional)
• Configuring a Relay Agent Information Reforwarding Policy (Optional)
• Enabling the DHCP Smart-Relay Feature (Optional)
Enabling the Cisco IOS DHCP Server and Relay Agent Features
By default, the Cisco IOS DHCP server and relay agent features are enabled on your router. To reenable
these features if they are disabled, use the following command in global configuration mode:
Command Purpose
Router(config)# service dhcp
Enables the Cisco IOS DHCP server and relay features on your router.
Use the no form of this command to disable the Cisco IOS DHCP server and relay
features.