Binary Math for IPv4 Subnetting

Being able to accurately convert between decimal and binary is a critical skill for anyone who needs to perform subnetting on IP Version 4 (IPv4) addresses.  Being able to perform these conversions quickly becomes important when the goal is to pass timed exams such as those for Cisco certification.  Whether you're just learning to subnet or you're looking to improve speed and accuracy, these practice exams will serve you well.

This 'course' is made up of five separate practice tests, with each test consisting of 20 questions.  Two of the practice tests focus on converting binary numbers to decimal numbers.  Two other practice tests are aimed at converting decimal numbers to binary numbers.  The final test is a combination of 10 decimal to binary and 10 binary to decimal practice questions.  Tests 1 and 2 each allow 2 hours to complete, which works out to 6 minutes per question.  The third and fourth tests allow ninety minutes each, or 4-1/2 minutes per question.  The final test allows for one hour, or three minutes per question.

Tip: Students will find it helpful to write out the powers of 2 as shown below as they work through each test question.

128  |  64  |  32  |  16  |  8  |  4  |  2  |  1

For the purposes of this course, questions will use no more than 8 bits, meaning there will be no decimal numbers higher than 255, and no need to write out the powers of two any higher than what is shown in the table above.