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| Question ID 18589 | Which option describes how a VTPv3 device responds when it detects a VTPv2 device on
a trunk port?
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| Option A | It sends VTPv3 packets only.
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| Option B | It sends VTPv2 packets only.
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| Option C | It sends VTPv3 and VTPv2 packets.
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| Option D | It sends a special packet that contains VTPv3 and VTPv2 packet information.
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| Correct Answer | C |
Explanation Explanation: When a VTP version 3 device on a trunk port receives messages from a VTP version 2 device, the VTP version 3 device sends a scaled-down version of the VLAN database on that particular trunk in a VTP version 2 format. A VTP version 3 device does not send out VTP version 2-formatted packets on a trunk port unless it first receives VTP version 2 packets on that trunk. If the VTP version 3 device does not receive VTP version 2 packets for an interval of time on the trunk port, the VTP version 3 device stops transmitting VTP version 2 packets on that trunk port. Even when a VTP version 3 device detects a VTP version 2 device on a trunk port, the VTP version 3 device continues to send VTP version 3 packets in addition to VTP version 3 device 2 packets, to allow two kinds of neighbors to coexist on the trunk. VTP version 3 sends VTP version 3 and VTP version 2 updates on VTP version 2-detected trunks. Reference: http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst6500/ios/12- 2SX/configuration/guide/book/vtp.html
| Question ID 18590 | Which mechanism can be used on Layer 2 switches so that only multicast packets with
downstream receivers are sent on the multicast router-connected ports?
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| Option A | IGMP snooping
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| Option B | Router Guard
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| Option C | PIM snooping
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| Option D | multicast filtering
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| Correct Answer | C |
Explanation Explanation: Ideally, the Layer 2 device should forward the multicast transmission only out ports to which receivers are connected and also out any ports that are connected to downstream multicast routers. This configuration requires a Layer 2 device to be able to determine the ports on which multicast routers and receivers for each separate (S,G) or (*,G) multicast group are located. To facilitate intelligent forwarding of multicast traffic on the LAN, Cisco Catalyst switches support two mechanisms: ✑ IGMP snooping — The switch listens in or "snoops" IGMP communications between receivers and multicast routers. This snooping enables the switch to determine which ports are connected to receivers for each multicast group and which ports are connected to multicast routers. ✑ Cisco Group Management Protocol (CGMP) — The switch communicates with multicasts routers, with multicast routers relaying group membership information to switches. Reference: https://www.informit.com/library/content.aspx?b=CCNP_Studies_Switching&seqNum=59