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Chapter 9
Multicast
Answers to Review Questions
1.
D. The valid range of IP addresses for multicast start at 224.0.0.0.
Anything lower than that is not within the specified range. The range
continues until 239.255.255.255, which specifies the entire Class D
network. That makes D the correct answer.
2.
B, C, D. The first response is outside of the valid range for IP multi-
cast addresses. The other choices are valid host addresses within the
range.
3.
A. Broadcast communications use the broadcast IP or MAC address
to communicate information to all hosts. Multicast data is sent
only to hosts that subscribe to groups that are active on the
network.
4.
C. IANA reserved the address 224.0.0.1 for all multicast hosts on a
local segment. This address is not routed or forwarded by routers.
5.
B. IANA reserved the address 224.0.0.2 to indicate all local multicast
routers. Again, this address is not forwarded by any routers in the
network.
6.
A. The first 24 bits of a MAC address were assigned the value of
0x01005e for all multicast addresses. The other values do not desig-
nate a multicast MAC address.
7.
D. Because only one half of one OEM was allocated for individual
multicast MAC addresses, only 23 bits transfer from the layer 3 IP
address.
8.
C. Due to the lost 5 bits in the mapping, a value of 2
5
is left ambiguous.
9.
B. The MAC prefix is 01-00-5E. You know you don't have to worry
about the lost bits because the second octet of the IP address is less
than 127. Therefore, the value is 02. The last two octets are mapped
with no problem.
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