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This chapter is from the book

This chapter is from the book

CCENT ICND1 100-105 Exam Cram, 3rd EditionCCENT ICND1 100-105 Exam Cram, 3rd Edition

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This chapter is from the book

This chapter is from the book

CCENT ICND1 100-105 Exam Cram, 3rd EditionCCENT ICND1 100-105 Exam Cram, 3rd Edition

Learn More Buy

Topic: Compare and contrast IPv4 address types

CramSaver

  1. When you send information from one system to another system in the network without the intent of the data reaching any other system, this is what type of traffic?

    _________

  2. What type of traffic uses the address range with 224-239 in the first octet?

    _________

  3. What destination MAC address do you find in an ARP frame when it is sent from a workstation that needs Layer 3 to Layer 2 address resolution?

    _________

Answers

  1. Unicast

  2. Multicast

  3. The broadcast address

Modern networking systems use three main forms of addressing in order to communicate in the network:

  • Unicast

  • Broadcast

  • Multicast

Unicast transmission is most likely what you think of first. For example, you are in a home network with an IP address of 192.168.1.2, and you want to send data to print to a printer located at 192.168.1.10. You do not intend for any other system to receive this traffic. This is a classic example of unicast IPv4 traffic.

When you have a system that must send a frame to all members of the network, this is termed a broadcast. At Layer 2, the destination broadcast address is FF:FF:FF:FF:FF:FF. At Layer 3, an example of a broadcast IPv4 address is 255.255.255.255. Remember, there is another type of broadcast, however. This is when a packet is destined for all of the members of a subnet. You and I calculated the broadcast address for subnets in this chapter. So, for example, the broadcast address for Subnet 10.10.0.0/20 is 10.10.15.255.

NOTE

Because a directed broadcast to a remote subnet can introduce many potential security issues, most routers give you the opportunity to enable or disable directed broadcast capabilities.

What if you want your device to “tune into” traffic in much the same way we tune into a television station in order to enjoy a broadcast of some show? The network equivalent of this is multicasting. Remember, the multicast address range is 224–239 in the first octet. Computers can “subscribe” to or “join” the multicast group by participating in this address scheme (in addition to their unicast address). Multicast is a way of sending one message (or set of packets) to multiple hosts across multiple networks and subnetworks. Some routing protocols use multicast addressing. When you enable RIP on your router, it starts listening for traffic destined for its 224.0.0.9 address as this is the address used to send traffic to all RIPv2 routers.

CramQuiz

  1. Your system is sending email to the local SMTP server. What type of IPv4 traffic is this most likely given that these two systems have communicated seconds ago?

    cir.jpg A. Broadcast

    cir.jpg B. Multicast

    cir.jpg C. Unicast

    cir.jpg D. Anycast

  2. EIGRP uses 224.0.0.10 in its operation. What type of address is this?

    cir.jpg A. Unicast

    cir.jpg B. Broadcast

    cir.jpg C. Multicast

    cir.jpg D. Anycast

  3. What does it mean when you see FF:FF:FF:FF:FF:FF as the destination address in an Ethernet frame?

    cir.jpg A. It means the frame is a multicast.

    cir.jpg B. It means the frame is a unicast.

    cir.jpg C. It means the frame should be dropped.

    cir.jpg D. It means the frame is a broadcast.

CramQuiz Answers

  1. C is correct. Although an ARP broadcast may initially be needed, because these systems have already communicated, the traffic can be sent unicast.

  2. C is correct. 224.0.0.10 is the all-EIGRP-routers multicast address.

  3. D is correct. The destination address of FF:FF:FF:FF:FF:FF is a reserved MAC address to indicate a broadcast.

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