Why is this a multicast address? 1

[niqsterd]

Hi,
I understand that answer "E" below is correct but why is answer "A" a multicast address? thank You.



Given the choices below, which address represents a unicast address?
A. 224.1.5.2
B. FFFF. FFFF. FFFF.
C. 192.168.24.59/30
D. 255.255.255.255
E. 172.31.128.255/18
Answer: E
Explanation:
172.31.128.255 is the only unicast address. It seems to be a broadcast address, because of
255 in the last octet. However, the broadcast address for this network is actually
172.31.131.255.
Incorrect Answers:
A: 224.1.5.2 is a multicast address.
B: This is a broadcast layer 2 (data link) address.
C: Using a /30 for the subnet mask,

 

[burtsbees]

Class C addresses begin at 192.0.0.1, and end with 223.255.255.254, with 192.0.0.0 being a network address, and 223.255.255.255 being a broadcast address. The Class D class of IP addresses are reserved for multicast addresses, so are there for unable to be assigned to nodes as a usable routeable IP address. This range starts at 224.0.0.0 and ends at 239.255.255.255
240.0.0.0 starts the Class E range, and ends with 255.255.255.255, and this is an experimental range. Hope this helps.

Burt

 

[CiscoGuy33]

Class A Network - the binary address starts with 0, therefore the decimal number can be anywhere from 1 to 126. The first 8 bits (the first octet) identify the network and the remaining 24 bits indicate the host within the network. An example of a Class A IP address is 102.168.212.226, where "102" identifies the network and "168.212.226" identifies the host on that network. The number 127 is reserved for loopback and is used for internal testing on the local machine.)

Class B Network - the binary addresses starts with 10, therefore the decimal number can be anywhere from 128 to 191. (The first 16 bits (the first two octets) identify the network and the remaining 16 bits indicate the host within the network. An example of a Class B IP address is 168.212.226.204 where "168.212" identifies the network and "226.204" identifies the host on that network.

Class C Network - the binary addresses starts with 110, therefore the decimal number can be anywhere from 192 to 223. The first 24 bits (the first three octets) identify the network and the remaining 8 bits indicate the host within the network. An example of a Class C IP address is 200.168.212.226 where "200.168.212" identifies the network and "226" identifies the host on that network.

Class D Network - the binary addresses starts with 1110, therefore the decimal number can be anywhere from 224 to 239. Class D networks are used to support multicasting.

Class E Network - the binary addresses starts with 1111, therefore the decimal number can be anywhere from 240 to 255. Class E networks are used for experimentation. They have never been documented or utilized in a standard way.


E.A. Broda
CCNA, CCDA, CCAI, Network +

 

[Chigy]

niqsterd: Just a pick on your solution: the broadcast for 172.31.128.255/18 is 172.31.191.255.
(network: 172.31.128.0 255.255.192.0)

Good expanations burtsbees and E.A. Broda.