Cisco CCNP Certification Practice Exam For BSCI Study:

Multicasting Practice Exam Questions (And Answers!)

By Chris Bryant, CCIE #12933

Understanding multicasting is more and more important when you're working with today's networks, and it's a vital topic on your BSCI exam as well!

To help you prepare for total success on exam day and beyond, here are 10 practice exam questions on multicasting. Answers can be found at the bottom of the page. Enjoy!

1. We all know the Class D address range 224.0.0.0 - 239.255.255.255 is reserved for multicasting. What's the general purpose of each of the following subnets or single addresses from that range?

A. 224.0.0.0 - 224.0.0.255

B. 239.0.0.0 - 239.255.255.255

C. 224.0.0.6

D. 224.0.0.12

2. Describe the basic process and purpose of the RPF check.

3. What device sits at the top of a multicast tree?

A. The source of the packets

B. The destination of the packets

C. A multilayer switch

D. The root bridge

4. When IGMPv1 is in use, a host can join a multicast group in one of two ways. Identify them from the following list.

A. Answering a Membership Request

B. Issuing a Membership Request

C. Answering a Membership Report

D. Issuing a Membership Report

5. A host wants to leave a multicast group. IGMPv1 is in use. What action will the host take in order to leave the group?

A. Issue a Membership Report

B. Issue a "Leave Group" message

C. Nothing

D. Respond to a Membership Report with a packet with the "Leave Group" bit set

6. A host wants to leave a multicast group. IGMPv2 is in use. What will the host do in order to leave the group?

A. Send a message to 224.0.0.2

B. Send a message to 255.255.255.255

C. Send a message to 224.0.0.12

D. No message will be sent by the host

7. You're deciding on which PIM method to use. The sender and recipients of multicast traffic are physically close, and there will be few senders. However, you've got a relatively large number of recipients. What is your best choice?

A. PIM Sparse mode

B. PIM Dense mode

C. PIM Sparse-Dense mode

D. PIM Broadcast mode

8. What address from the reserved multicast range is reserved for Prune messages?

9. In the following configuration, what does the "rp-address" refer to?

R1(config)#ip multicast-routing
R1(config)#ip pim rp-address 172.12.123.1
R1(config)#int s0
R1(config-if)#ip pim sparse

10. What command resulted in the following output?

R3# ?
Group: 224.0.1.40, RP: 172.12.123.1, v1, uptime 00:12:43, expires 00:04:20

Here are the answers!

1. The four ranges and their purposes are listed below.

224.0.0.0 - 224.0.0.255: Reserved for network protocols. This is the local network control block. Packets in this range will not be forwarded by routers, so they remain "local".

239.0.0.0 - 239.255.255.255: This is the Class D private address range. Like the other private ranges, these addresses can't be routed, so they can be reused from one network to another. This block of addresses is the administratively scoped block.  These addresses are also called limited scope addresses.

224.0.0.6: This is the "All OSPF DRs" address.

224.0.0.12: This multicast address is used by HSRP version 2.

2. The RPF Check is run against any incoming multicast packet.  The multicast router examines the interface that the packet arrived on.  If the packet comes in on an upstream interface - that is, an interface found on the reverse path that leads back to the source - the packet passes the check and will be forwarded.  If the packet comes in on any other interface, the packet is dropped.

3. (A). The source of the mulicast packets will be the "top" of the multicast tree.

4. (A, D). The host can either send a Membership Report or respond to an incoming Membership Request.

5. (C). In IGMP v1, the host cannot send a specific "I Quit" message.

6. (A). IGMPv2 hosts can send a Leave Group message to the reserved multicast address 224.0.0.2, the "all routers on this segment" address. 

7. (B). That's a perfect scenario in which to run PIM Dense.

8. Prune messages are sent to 224.0.0.13.

9. The "RP" is the rendezvous point on the multicast tree. The RP serves as a kind of "central distribution center", meaning that a shared tree will create a single delivery tree for a multicast group.

10. Speaking of RPs, that output is the result of the show ip pim rp command.

Look for more CCNP practice exams and tutorials right here at The Bryant Advantage!

To your success,

Chris Bryant

CCIE #12933

chris@thebryantadvantage.com