You may not always have a "tool" available to calculate for you. I've been in several customer meetings where I was required to come up with network diagrams, including subnet masks, ad hoc. If I had needed to have them wait til I could power up my laptop, then use a program to do the work, it would have looked unprofessional and reflected badly upon myself as an engineer and my company. The ability to calculate, in your head or on paper, subnet masks impresses clients, co-workers and bosses and keeps you sharp mentally. Mark Baker CCNP looking for a job (but not because I can't calculate subnets in my head!) -----Original Message----- From: Ken [SMTP:[EMAIL PROTECTED]] Sent: Wednesday, August 08, 2001 12:30 PM To: [EMAIL PROTECTED] Subject: Why Should the Binary Math Method Be Used to Subnet [7:15306] This is a study group so I have a question for which I need some education. I am not looking for a flame war, just education. The question I have is of what use is the binary math method of subnetting as compared to just using a program that does subnetting? If the point to the exercise is to produce a plan for subnetting that can then be entered into each device on the network or into a DHCP server setup, what else is achieved by doing this manually? It seems to me that the point is not the journey, but the arrival at the destination. Indeed arrival as quickly as possible, with the least source of error. As Cisco even says; "The purpose of this tool is to provide a way to calculate IP subnetting which is fast, easy, and error free. Doing such calculations manually is time consuming and susceptible to common mathematical mistakes, especially in conversions between binary and decimal numbers." So what is it I am not understanding? Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=15311&t=15311 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]