what is unicast address

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alt.certification.ciscoGiven 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

I know the right answer is 'E',while I want to know sth about unicast
address.


Re: what is unicast address
leeloo.au@gmail.com wrote:

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An unicast address corresponds to a single interface on a single host, while
a multicast address can correspond to multiple hosts.
Unicast addresses range goes from 0.0.0.0 to 223.255.255.255, but of course
not all of them are usable.
What do you want to know?


Re: what is unicast address
A unicast is simply an address that points to one particular host, as opposed
to multiple, or even all, hosts like a multicast or broadcast. Here is how
your list breaks down:

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Since the first octet of this address is 224 it falls in the multicast range
so it is not a unicast address.

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This is the target MAC address of a broadcast, so again, not a unicast.

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This one is here to trick you. If you work out the subnet it is 192.168.24.56
through 192.168.24.59. Since 192.168.24.59 is the last IP in the range, it is
the broadcast address. In binary, all the host bits are ones. So this address
actually referes to all of the hosts in the subnet and not just one.

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This represents a broadcast address sent to anyone who is listening on a
shared network segment.

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Again, if we work out the subnet here the range includes 172.31.128.0 through
172.31.191.255. Since 172.31.128.255 falls in between those two numbers, it
is a host IP. In other words, it referes to one particular host, making it a
unicast address.

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Hope that helps,

Joseph

Re: what is unicast address
thanks all of you,i think i get what i need!


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