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CCENT subnetting question

Greetings good people,

I am having trouble understanding third octet identification with class B addressing when dealing with /25 masking...

my question is what/how do we deal with the third octet as far as identifying it in dotted decimal... /25  ........  is the answer as simple as saying "follow the new mask designation"  for identifying the network portion?

if you could follow my line of thinking here for a second:  overall, it does not matter that it is a class B nor what mask a B address has....because we're changing it to /25 right?

and with that thought, there are now three octets (plus one bit of the fourth) which designate the network portion of the dotted decimal address....  leaving the host portion identifying 1-126  ..

I ask because I had confusion on what to do with the third octet.... but!! if I did the ANDing process between the /25 and it would have been clear?

as mud.

thanks for any input...

Hall of Fame Super Blue

Re: CCENT subnetting question

The subnet mask is the key as you say. can be read as - leave the first 3 octets alone ie. they stay as they are and only on the 4th octet will anything change so translates to -

Network =

Hosts = -> 126

broadcast =

from your explanation you seem to have pretty much understood how it works.


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