During the Cisco IP Phone registration process the TFTP download fails. What are two reasons for this issue'? (Choose two)

While DNS can be used to resolve a TFTP hostname, it's not strictly 'needed' if Option 150 directly provides an IP address; the core issue of TFTP failure is knowing the TFTP server's address.

For an IP phone to download configuration files from a TFTP server, it must first know the TFTP server's IP address. If this information is missing, the phone cannot initiate the TFTP connection, leading to a download failure.

The IP phone needs the TFTP server address to get its configuration files, which then contain the Cisco UCM subscriber node details, so not knowing subscriber nodes directly wouldn't prevent the TFTP download itself.

DHCP Option 100 is not a standard option for providing the TFTP server address for Cisco IP Phones; Option 150 is the dedicated option for this purpose.

DHCP Option 150 is the standard method for provisioning Cisco IP Phones with the IP address of the TFTP server. If Option 150 is not specified or contains an incorrect IP address, the phone will be unable to locate and connect to the TFTP server for file downloads.