Study the Exhibit below carefully:
London#show vtp
VTP Version: 2
Configuration Revision: 0
Maximum VLANs supported locally: 64
Number of existing VLANs: 5
VTP Operating Mode: Client
VTP Domain Name: London
VTP Pruning Mode: Disabled
VTP V2 Mode: Disabled
VTP Traps Generation: Disabled
Based on the information given above, what is the VTP function of this particular switch?（）

You are a senior network administrator at TestKing and your trusty junior administrator tells you that he failed his task of adding VLAN 50 to a Catalyst switch in the network. You enter in the 'show vtp status' command and get this output:
TK2# show vtp status
VTP Version :2
Configuration Revision :7
Maximum VLANs supported local :68
Number of existing VLANs :8
VTP Operating Mode :Client
VTP Domain Name :corp
VTP Pruning Mode :Disabled
VTP V2 Mode :Disabled
VTP Traps Generation :Disabled
MD5 digest :0x22 0xF3 0x1A
Configuration last modified by 172.18.22.15 at 5-28-03 1t:53:20
What commands must be issued on this switch to add VLAN 50 to the database?（）

There are 2 switches in the Testking LAN, with no routers. Ports 1, 2 & 3 are assigned to VLAN 1 in switch 1 and 2 and ports 4, 5 & 6 are assigned to VLAN 2 in both switches. These two switches are connected together via a trunked link.
Which of the conditions below would verify trunk and VLAN operation?（）

A TestKing.com technician is troubleshooting connectivity problems between two routers that are directly connected through the serial line. The technician notices that the serial line is up but cannot see any neighbors displayed in the output of the show cdp neighbors command.
In which OSI layer is the problem most likely occurring?（）