CST3607 Class Notes 2022-02-22

News & Tools

Assignment #1 Debriefing

Subnetting Tutorial & Reference Page

Subnetting Tips/Notes

  • If no mask/prefix is given, then borrow bits starting from the “Class” boundary of the IP address.
  • If a mask/prefix is given, then the given mask/prefix is the result of subnetting.  (Borrow bits from the “Class” boundary to the given mask/prefix.)
  • The total number of subnets must be a power of 2.
  • The total number of hosts must be a power of 2.
  • Is the question asking for “subnets” or “hosts”
    • If you’re asked for the # of hosts, then you must determine how many bits are needed to get that # of hosts, then subtract those bits from the 32 IPv4 bits, to determine the network bits / mask / prefix.
  • Determine the number of subnets: 2 [number of bits borrowed].
  • Determine the total number of addresses: 2 [the number of host bits].
  • Add the Wildcard mask to the network/subnet address to determine the broadcast/last address in the network/subnet.
  • Block Size:
    • The block size (256 – [The interesting octet]) is best used to determine the increment of the subnets.
    • The interesting octet is the last octet, from the left, that you borrowed bits from.
    • The “block size” is the increment from one subnet to the next, within the “interesting” octet. It is not the number of addresses per subnet.
  • Practice makes improvement!

We’ll cover Large Number of Subnets and Decimal to Base-256 dotted-decimal conversion during our next class


Do: Assignment #2: Due before Thurs. Feb. 24, 2022 6pm EST

  • Download the Assignment
  • Important: Make sure to read and understand the instructions on how to handle the protected PDF
  • If you have any issues completing all parts of every question on the assignment, e-mail me with the question # and the specifics you need assistance with.
  • No late assignments will be accepted.



Make sure to always have access to a calculator which has an Exponent function (^key) ( x) for every class.

Better Focus and Efficient Studying When Not Multitasking