Cisco CCNA (200-301)IP ServicesMedium
A network administrator is troubleshooting an issue where a newly deployed VoIP phone is not registering with the call manager. The phone is configured to use DHCP and relies on Option 150 to get the TFTP server address for its configuration files. Which command would the administrator use on the Cisco DHCP server to verify if Option 150 is being correctly provisioned?
- Ashow ip dhcp conflict
- Bshow ip dhcp binding
- Cshow running-config | section dhcp
- Dshow ip dhcp server statistics
Show answer & explanationAnswer & explanation
Correct answer: C. show running-config | section dhcp
To verify if DHCP Option 150 (TFTP server address) is configured and being offered by the Cisco DHCP server, the administrator needs to inspect the running configuration. The 'show running-config | section dhcp' command will display all DHCP-related configurations, including any custom options like Option 150.
Why the other options are wrong
- A. This command shows any IP address conflicts detected by the DHCP server.
- B. This command shows the IP address leases granted by the DHCP server, not the options being offered.
- D. This command displays general statistics about the DHCP server's operation, such as messages sent and received, but not specific option configurations.
DHCP Option 150
A DHCP option used by Cisco IP phones to obtain the IP address of a TFTP server where their configuration files are stored.
- Specific to Cisco IP phones.
- Provides TFTP server IP address.
- Configured within a DHCP pool using 'option 150 ip [address]'.
Memory trick: To check what the DHCP server is 'saying' (options), you must 'read its mind' (running config).