Greets all. If i make a mistake in my explanation of this, then please someone jump in and correct me. I'm still learning a lot of this. 1. Classfull Addressing The basic thing to remember with classful addressing is any router using this addressing scheme DOES NOT include the subnet mask within their router updates to other devices. All routers associated with subnets on the network (be it a class a, b or c network) will therefore have to have the same subnet mask to ensure correct communication and updates between devices. 2. Classless Addressing Classless Addressing was created to address the pitfalls of glassful addressing. The sublet mask is advertised for each route in the router updates. This can be set manually. 3. VLSM. VLSM. is tied into Classless addressing in a way. I have not progress that far in my studies yet so let me know how you fair. Dyland ------------------------------------------------------ hi friends Could anybody give explanation for the followibg terms. 1) classful addressing 2) classless addressing 3) VLSM. I did go through routing 2.0 book. but i could not understand the concept. thanks in advance. bye ravee _________________________________ FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]