ICND1: Interconnecting Cisco Networking Devices Part 1 (CCENT, legacy) — Question 7

Configuration of which option is required on a Cisco switch for the Cisco IP phone to work?

Answer options

• A. PortFast on the interface
• B. the interface as an access port to allow the voice VLAN ID
• C. a voice VLAN ID in interface and global configuration mode
• D. Cisco Discovery Protocol in global configuration mode

Correct answer: C

Explanation

The correct answer is C because defining a voice VLAN ID in both interface and global configuration modes allows the switch to correctly identify and segregate voice traffic. Option A is incorrect as PortFast is not required for IP phone operation. Option B is too narrow as it does not address the need for VLAN configuration, and Option D is unrelated to the basic operation of Cisco IP phones.