Verifying the DHCP Binding Database

Purpose

Verify that the DHCP binding database reflects your DHCP server configuration

Action

From operational mode in the CLI, to display all active bindings in the database, enter the show system services dhcp binding command. To display more information about a client, including its DHCP options, enter the show system services dhcp binding address detail command, replacing address with the IP address of the client. Finally, enter the show system services dhcp conflict command.

The DHCP binding database resulting from the configuration defined in Table 73 is displayed in the following sample output.

IP Address   Hardware Address   Type          Lease expires at
30.1.1.20  00:12:1e:a9:7b:81  dynamic       2007-05-11 11:14:43 PDT

    IP address           3.3.3.2
    Hardware address     00:a0:12:00:13:02
    Pool                 3.3.3.0/24
    Interface  fe-0/0/0, relayed by 3.3.3.200

Lease information:
    Type                 DHCP
    Obtained at          2004-05-02 13:01:42 PDT
    Expires at           2004-05-03 13:01:42 PDT
    State                active

DHCP options:
     Name: name-server, Value: { 6.6.6.6, 6.6.6.7 }
	 Name: domain-name, Value: mydomain.tld
    Code: 32, Type: ip-address, Value: 3.3.3.33

Detection time Detection method Address
    2004-08-03 19:04:00 PDT ARP 3.3.3.5
    2004-08-04 04:23:12 PDT Ping 4.4.4.8
    2004-08-05 21:06:44 PDT Client 3.3.3.10

Meaning

Verify the following information:

• For each dynamic binding, verify that the IP address is within the range of the configured IP address pool. Under Lease Expires, verify that the difference between the date and time when the lease expires and the current date and time is less than the maximum configured lease time.
• For each static binding, verify that the IP address corresponds to the MAC address displayed under Hardware Address (as defined in the static-binding statement in the configuration). Under Lease Expires, verify that the lease expiration is never.
• In the output displayed by the show system services dhcp binding address detail command, verify that the options under DHCP options are correct for the subnet.
• Verify that the show system services dhcp conflict command does not display any conflicts.

Related Topics

For complete descriptions of the show system services dhcp command and output, see the JUNOS System Basics and Services Command Reference.