https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst2960x/software/15-0_2_EX/vlan
/configuration_guide/b_vlan_152ex_2960-x_cg/b_vlan_152ex_2960-x_cg_chapter_0110.pdf Untagged traffic from the device attached to the Cisco IP Phone passes through the phone unchanged, regardless of the trust state of the access port on the phone.

SNMP is an application-layer protocol that provides a message format for communication between SNMP managers and agents. SNMP provides a standardized framework and a common language used for the monitoring and management of devices in a network.The SNMP framework has three parts:+ An SNMP manager+ An SNMP agent+ A Management Information Base (MIB)The Management Information Base (MIB) is a virtual information storage area for network management information, which consists of collections of managed objects.With SNMP, the network administrator can send commands to multiple routers to do the backup

TFTP (Trivial File Transfer Protocol) is a simple file transfer protocol that is often used to transfer configuration files or firmware to network devices, such as routers or switches, during the boot process. TFTP is lightweight and lacks advanced features like authentication or encryption, making it suitable for basic file transfer operations in situations where security is not a primary concern. Therefore, option A accurately describes one of the primary capabilities of TFTP. It is commonly used to load configuration files onto systems, particularly those without extensive data storage devices, during the initialization or configuration process.

https://www.cisco.com/c/en/us/td/docs/wireless/controller/7-5/configuration-guide/b_cg75
/b_cg75_chapter_0100010.html