IPv4 Subnets Welcome to the IPv4 Subnets practice simulator. This simulator allows you to practice your knowledge and skills of IP subnetting. Please select from the following activities. Practice IP subnetting and get instant feedback on how to correct any problem areas. Challenge yourself and see how many problems you can do without any help. Move forward only after you finish a problem. Prepare yourself for a test; take a self-assesment and get a report on how well you performed.