正确答案:DD 解析:Explanation:The VTP (VLAN Trunking Protocol) is a Cisco Layer 2 messaging protocol that manages the addition, deletion, and renaming of VLANs on a network-wide basis. It allows for VLAN information to span multiple switches within the switch domain.Incorrect Answers:A. STP is a switching protocol but it is used for preventing network loops.B. GVARP is an actual protocol used in switch administration, but it beyond the scope of what a CCNA is expected to know.C. SNMP is a protocol used for managing and monitoring networksE. DHCP is the Dynamic Host Configuration Protocol, which allows for PC's to obtain their IP address dynamically upon booting up, along with their DNS and default gateway information.