First you decide how many networks you need. Then you determine the subnet mask that will allow enough hosts on each network. Finally, you list the host addresses available for each network. It is a good idea to map out your addressing scheme on a piece of paper before doling out addresses to hosts. A good addressing scheme allows for growth, efficiently uses available address space, and follows an organized format. Good addressing leads to efficient troubleshooting, better security, and more uptime for your precious, yet forever impatient, users. You can further review the topics from today on pages 193–216 of CCNA Flash Cards and Exam Practice Pack (CCENT Exam 640-822 and CCNA Exams 640-816 and 640-802), Third Edition.