Date: Tue, 06 Feb 2007 18:08:45 -0600 (Central Standard Time)
   From: Mark Jacobson <jacobson@math-cs.cns.uni.edu>
     To: 810-023-01-spring@uni.edu
Subject: [810-023-01-SPRING] Subnet Masks, via Excel and Photoshop illustration...

Hi 023 students,

The subnet mask 255.255.224.0 quiz one problem is graphically
illustrated for the 191.202.0.0 class B network from QUIZ ONE
and from Monday's class.

I generated a bunch of random IP numbers between 0 and 255 for the
Y and the Z octets, of the w.x.y.z format.

Of course w is 191, and x is 202 for 191.202.0.0 and with
                                        w  x  y z

           y being the octet that has its first three bits
             used to specify one of up to 8 specific SUBNETworks
             that network 191.202.0.0 can have, courtesy

              of subnet mask 11111111.11111111.11100000.00000000
                             nnnnnnnn.nnnnnnnn.ssshhhhh.hhhhhhhh
                                               ---
              you will see two Excel
              screen snapshots, annotated with Photoshop, that
              should move your understanding to the next level,
              or at least sow the seeds for harvesting a good
              understanding in the near future.

      http://math-cs.cns.uni.edu/~jacobson/023/subnetMasksFeb6th2007.gif

      http://math-cs.cns.uni.edu/~jacobson/023/subnetMasksFeb6th2007b.gif

      http://math-cs.cns.uni.edu/~jacobson/c023.html

    We can answer questions BEFORE the quiz tommorrow, if anyone
    has any.  That would be nice.

    Mark